Background

In this section of the website you can obtain a summary overview of the key climate changes that are projected to affect the region by the period 2040 – 2070 (commonly referred to as ‘the 2050s’). 

These projections are based on the results from more local scale modelling that was undertaken specifically for this study.  The projected results are compared against a baseline period of 1960 – 1990 (commonly referred to as ‘the 1970s’). 

This section of the website contains:

• A summary of the main impacts affecting the region - this is provided as a Regional report.

• More detailed description of the projected changes - this can be found in the Sub-regional section.

Also provided is a Climate Glossary intended to help explain some of the terms used and to further describe some of the parameters that have been investigated.

If you wish to view more detail relating to the projected climate changes, this can be found under the section Climate Projections – Detail, which provides detailed results under the headings of:

• Temperature;
• Rainfall;
• Wind;
• Snow and frost;
• Humidity;
• Soil moisture; and
• Sea level and surges.

 

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| North Yorkshire | West Yorkshire | Humber | South Yorkshire |

 

NORTH YORKSHIRE

Annual and Seasonal Average Temperature
The annual average daily mean temperatures across North Yorkshire are projected to increase by 1.8 ºC across the whole sub-region by the 2050s as projected by EARWIG.  The only variation from this pattern is shown in York, where the increase is expected to be slightly higher at 1.9ºC.

Seasonally, the average daily mean temperature is projected to rise the least during winter, with an increase of 1.4 ºC.  The largest projected increases are expected during the summer months, ranging from 2.1 ºC to 2.4 ºC, with the highest increases seen in York and the lowest in the upland Yorkshire Dales. Spring and autumn also see considerable increases in average temperature with an increase of 1.6 ºC in the spring and 2.0 ºC in the autumn.

Annual and Seasonal Average Maximum and Average Minimum Temperatures
Annual (and summer) average maximum temperatures are expected to increase by between 2.8 and 3.0 ºC across the whole sub-region, with the greatest actual average annual (and summer) temperatures reaching 29.9 ºC in York.  The Yorkshire Dales and North York Moors with see the lowest increases, with average maximum temperatures of 27.2 ºC.  The coast will see the same temperature increase as seen in the uplands but will have a higher average maximum temperature of 28.1 ºC.

Winter average maximum temperatures are expected to increase by approximately 1.4 ºC with little variation across the sub-region.  Spring average maximum temperatures are projected to rise by 1.6 ºC whilst autumn average maximum temperatures are projected to increase by approximately 2 ºC.  As for the other seasons, there is little variation across North Yorkshire.

Annual and seasonal average minimum temperatures are also projected to increase across North Yorkshire.  Annual and winter average minimum temperatures are projected to increase by between 1.5 and 1.7 ºC.  This increase results in only the highland of the Yorkshire Dales and the North York Moors capable of achieving sub-zero temperatures with average minimum temperatures at the coast, lowlands and metropolitan areas remaining just above 0 ºC.

Summer average minimum temperatures are projected to increase by 1.8 ºC in all areas except built up areas of York where the increase is projected to be 2.0 ºC.

Severe Temperatures and Heatwaves
Temperatures associated with both hot and cold extreme temperature events, and the frequency in the number of heat waves can be expected to increase over this sub-region.

For the 5th percentile (extreme cold) events, temperatures are projected to increase by up to 2.0 ºC, however these will remain below zero in the uplands during the spring, autumn and winter.  In the lowlands of North Yorkshire, extreme cold temperatures are only expected below zero during the winter months with the coldest temperatures in spring expected to be 1.9 ºC.

For the 95th percentile (extreme hot) temperatures, values will increase throughout the sub-region.  The greatest increases will be experienced in the summer and autumn of up to 3.1 ºC.  The lowest increase is projected for the coast and North York Moors whilst the highest increase is expected in York.

The annual average number of hot days will vary throughout North Yorkshire. In the uplands the increase will be around 0.4 days with up to a 3.2 day increase in the city of York.  Seasonally, there will be little or no change during the spring, autumn and winter.

The number of 2-day heat waves is projected to increase by 0.2 days annually in the city of York but there will be no change across the remainder of North Yorkshire.

Annual and Seasonal Rainfall
Average annual rainfall is expected to decrease over North Yorkshire. The change will be greatest in the lowland areas, where a reduction of around 5% is projected. In upland areas, the reduction is projected to be approximately 2.5%.

Seasonally, there will be an increase in winter rainfall of 12% to 16% while little relative change will occur during the spring. Summer will experience the greatest decrease in rainfall with a range from -22.4% to -25.6%.  The greatest reductions are projected to occur in the uplands of the North York Moors and Yorkshire Dales, whilst the smallest reduction is projected at the coast.

Severe Rainfall and Rainfall Accumulations
The upland areas of North Yorkshire, mainly the North Yorkshire Moors and the Yorkshire Dales, will experience an increase in the amount of rain falling during rainfall events that exceed the 50% Annual Exceedance Probability (AEP) across the range of event durations that have been projected (1, 2, 5 and 10 day). The greatest relative change is expected over the shorter duration events, such as the 1-day duration where an increase of 6.5% is projected over the North York Moors.

The remaining lowland areas are projected to see a decrease in the amount of rain falling during 50% AEP rainfall events and therefore accumulated rainfall. The relative changes will be greatest over the 1-day events reaching -2.5% (-0.8mm) but the absolute measured changes will be greater over the 10-day periods -2.5mm (-4%).

When analysing sub-daily rainfall events, those with a duration of 1 hour are projected to deliver 9% less rainfall in the 2050s than they do at present in the Yorkshire Dales, with small reductions seen across the whole of the sub-region.

This trend begins to reverse as the length of the rainfall event increases with amounts of rainfall increasing by up to 6% during events that persist for up to 12 hours.  In this case the greatest variations are seen in the North York Moors while the smallest variations are seen in the lowland and at the coast.

The amount of rain falling during the more extreme 5% AEP rainfall events will increase over the uplands but will decrease in the lowland areas of the region.

Dry Spells
EARWIG has projected the number of dry spell events occurring in the region, where there are 10 and 20 consecutive days with less than 0.2mm and 1mm of rainfall.  The number of such dry spells increase across the sub-region for all parameters.  For 10 consecutive days, the number of independent occasions ranges between 1.8 to 2.5 over the region, an increase between 39% and 96%.

20 consecutive days of little or no rain is far less likely to occur and as such the number of independent events ranges from 0.6 to 1.1.

Snowfall
The EARWIG projections show that the average annual number of days when snow falls will decrease over the entire region. This reduction will be greater in the upland areas of the North Yorkshire Moors and the Yorkshire Dales although the relative change will be felt to a greater effect in the lowland areas. This will be due to the baseline data already recording a proportionally higher number of snowfall days in the upland areas. This data is supported by the annual average water depth equivalent of snow per year, which shows the greatest absolute change in the upland areas (-57.9mm) but greatest relative change in the lowlands areas (-64.7%).

Seasonally, the greatest relative change will be experienced in the spring and autumn months resulting in an average reduction of 80.9% and 75.4% respectively for the whole of North Yorkshire. The greatest absolute change is in the upland areas during the winter where the Dales will see a reduction of 7 snowfall days and the Moors a loss of 5.2 days.

Frost
Annually, there will be a decrease in the average number of frost days per year. The greatest change is expected in the upland areas of the Yorkshire Dales and the North Yorkshire Moors with a loss of -33.7 and -30.9 days respectively. The lowland areas will experience a reduction of around 24 days throughout the year. 

Wind
The annual average wind speed for North Yorkshire ranges from 4.5m/s in the southern lowland area to 5.1m/s on the windy hilltops on the North Yorkshire Moors and coastal town of Scarborough. Overall, EARWIG projects a reduction of 0.1m/s for this sub-region although the city of York will see no change in its annual wind speed. The principal seasons that will experience reduced wind speeds are in the summer and autumn, the greatest reductions during the summer as greater temperature gradients are created. There are no projected changes in wind speed for the winter and spring.

Humidity and Vapour Pressure
Annually, there will be a decrease in humidity in the North Yorkshire sub-region. The greatest decrease will be experienced near to the city of York (-11.3%) and the smallest in the uplands of the Dales (-10.5%).

Seasonally, relative humidity is to change the most during the summer months with reductions from -12.7% in the coastal zone to -14.3% in York.

The annual average vapour pressure varies across North Yorkshire. There is expected to be a relative reduction in the far north of the sub-region (-0.2%) and a relative gain on the North Yorkshire Moors (0.1%). Elsewhere, the change is negligible. In terms of season changes, winter will see a general increase in vapour pressure and autumn an overall loss for the sub-region.

 

WEST YORKSHIRE

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Annual and Seasonal Temperature
West Yorkshire can expect an increase in annual average daily mean temperatures of 1.9 ºC from the baseline.

The smallest change in temperature expected seasonally will be during the winter with an increase of 1.4 ºC.  This is comparable to the expected temperature increase in spring of 1.6 ºC and subsequently 2.2 ºC and 2.4 ºC during autumn and summer.

Annual and Seasonal Maximum and Minimum Temperatures
Average maximum annual (and summer) temperatures are expected to increase by 3.0 ºC across the whole sub-region, with the greatest actual average maximum temperatures reaching 30.7 ºC in Leeds.  It is likely that western areas of West Yorkshire, such as the uplands around Todmorden or Marsden will experience changes in temperature similar to those upland areas further north where average maximum temperatures are projected to increase by 2.7 ºC.

Winter average maximum temperatures are expected to increase by approximately 1.2 ºC in Leeds.

Annual and seasonal average minimum temperatures are also projected to increase across West Yorkshire.  Annual and winter average minimum temperatures are projected to increase by 1.6 ºC which will leave the average minimum temperature just below freezing at -0.4 ºC.

Summer and autumn average minimum temperatures are projected to increase by 2.0 ºC in built up areas while in the uplands may only experience a rise of 1.8 ºC which will result in seasonal average minimum temperatures of 4.6 and 4.5 ºC respectively.

Severe Temperatures and Heatwaves
Temperatures associated with both hot and cold extreme temperature events, and the frequency in the number of heatwaves can be expected to increase over this sub-region.

Extreme cold temperatures in the 5th percentile are to increase by 1.7 ºC for all seasons with exception to the autumn where the temperature will increase by
2.0 ºC.

The 95th percentile extreme hot temperature increases throughout the seasons. The smallest change will be in winter with 1.1 ºC and by comparison, the greatest value change to be in the autumn with a 3.4 ºC increase where 5% of days have hotter temperatures than this value.

Annually, the number of hot days above 28 ºC will increase by 4.8 days for West Yorkshire. There will be no change during spring and winter. A small increase in the number of hot days is expected in autumn but the greatest will be experienced during the summer. The number of 2-day heat waves is to increase by 0.4 days annually.

Annual and Seasonal Rainfall
Annual average rainfall is expected to decrease by 4.3% in West Yorkshire, although seasonally decreases and increases will be felt in the summer and winter, respectively. Winter average rainfall is expected to increase by 14.6% compared to the reduction in rainfall of 23.7% during the summer months. Both spring and autumn will also experience a small reduction in rainfall.

Severe Rainfall and Rainfall Accumulations
West Yorkshire will experience a reduction in the amount of rainfall during 50% Annual Exceedance Probability (AEP) rainfall events across the durations of 1, 2, and 10 days. 50% AEP events of 5-day duration are not projected to experience any change. The greatest relative change will be over 2-day period events, with a reduction of 3.1%.

Rainfall during 5% AEP events will decrease over all the durations. The effects will be greater for the 1-day and 2-day events with a relative change of -6.3% and -7.9% respectively.

A similar trend is evident with the 1, 3, 6 and 12-hour 50% AEP extreme events. The greatest relative changes are projected for the 3-hour 50% and 10% AEP events which result in reductions of 1 and 1.2mm respectively.

Dry Spells
Additionally, there will be an increase in the number of dry spells through the sub-region. The number of dry spells of 10 days with less than 0.2mm and 1mm rainfall will range from 2.5 to 3, doubling the baseline. The absolute change of dry spells for 20 consecutive days with less than 0.2mm and 1mm rainfall are both to increase by 0.8.

Snowfall
The average number of days each year on which West Yorkshire will experience snowfall is projected to reduce by 62.9%. This is an absolute reduction of 2.8 days. To a similar effect, the actual amount of snow, measured in water depth equivalent, will be reduced by 10mm per year.

The relative change in seasonal snowfall days is greater in the spring and autumn although the actual number of days lost is greatest during the winter at 2.2 days. A similar trend occurs with the water depth equivalent of snow, where the average water depth equivalent is 7.7mm less in winter of the 2050s than in the baseline data.

Frost
EARWIG projects that there will be 24.9 fewer frost days per year in the 2050s than compared to the baseline data for the built up areas of West Yorkshire.  This accounts to a relative change of -42.9% which results in a mean value of 33.2 frost days for the 2050s.  It is likely that the higher elevated areas to the west and south of Leeds will not see such a dramatic reduction in frost (the reduction in frost days in Askrigg is only 34.8%).

Wind
Annually, average wind speeds in West Yorkshire are going to reduce minimally at a relative change of -0.7%. The greatest reduction in wind speed is set to be felt in the summer months with a relative change of -2.5%, a resultant loss of 0.1m/s and an increase of 0.9% in winter.

Humidity and Vapour Pressure
Changes in projected annual relative humidity for West Yorkshire show the second highest change in the whole of the study area, with an overall reduction of -11.4%. The greatest change of this parameter is during the summer months, for which there is a reduction of 14.6%.

Vapour pressure is set to increase in West Yorkshire, but only during the winter when there is projected to be an increase of 0.3%. Summer, autumn and spring are projected to receive reductions in vapour pressure between -0.1% and -0.2%.

HUMBER

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Annual and Seasonal Temperature
There is an expected average annual daily mean temperature increase of 1.9ºC across much of the Humber sub-region, although it is likely that conditions along the coast will be similar to those seen in Scarborough, thus resulting in an increase of 1.8ºC by the sea.

Seasonally, the greatest increase in average daily mean temperature will be expected during the summer with an increase of 2.3ºC resulting in average daily summer temperatures of 17.3ºC.  The expected increase during the autumn months is marginally lower than this, with an increase of 2.1ºC.  Winter results demonstrate the smallest increase, with average winter temperatures reaching 5.6ºC, an increase of 1.4ºC.  Spring temperatures are projected to rise just above this by 1.6ºC to an average daily of 9.6ºC.

Annual and Seasonal Maximum and Minimum Temperatures
Average maximum annual (and summer) temperatures are expected to increase by 2.9ºC across the whole sub-region, with the greatest actual temperatures reaching 29.3ºC in Hull. It is likely that eastern, coastal areas of the Humber sub-region, such as Bridlington will experience changes in temperature similar to coastal areas further north where maximum temperatures increase by 2.7ºC.

Annual and seasonal average minimum temperatures are also projected to increase across the Humber sub-region.  Annual and winter average minimum temperatures are projected to increase by 1.6ºC which will result in an average minimum temperature just below freezing at -0.7ºC.

Summer and autumn average minimum temperatures are projected to increase by approximately 1.8ºC in both built up and coastal areas.  Western areas of East Riding may experience slightly higher increases of up to 2.0ºC.  These increases are likely to result in summer average minimum temperatures of around 14ºC and autumn average minimum values of approximately 5.5ºC.

Severe Temperatures and Heatwaves
Temperatures associated with the coldest (5th percentile) extreme cold events, are projected to increase throughout of all the seasons.  The smallest increases are in the winter, spring and summer where increases of between 1.6ºC to 1.7ºC will result in overall extreme cold temperatures of -2.4ºC, 2.3ºC and 11ºC respectively. The autumn is projected to see a greater increase of 2.1ºC, resulting in mean 5th Percentile temperatures of 1.6 ºC.

In comparison, the extreme (95th percentile) hot temperatures will increase by a greater value of 3.1ºC during the summer months. Temperatures during the summer may reach the extreme temperature of 32.0ºC. During autumn, winter and spring, extreme hot temperatures are projected to increase by 2.9ºC , 1.0ºC and 1.9ºC respectively. 

The number of hot days, where the maximum temperature exceeds 28 ºC is expected to increase by an average of 2.1 days per year over the Humber sub-region. This increase is primarily expected during the summer with an increase of 0.1 days expected during the autumn.  The number of 2-day heat waves, where hot days occur consecutively is also projected to increase from 0 days to 0.1 days annually.

Annual and Seasonal Average Rainfall
Annual average rainfall is expected to decrease by 3.5% across the Humber region, with 631mm of rain per year expected in Hull.  Coastal areas are expected to see a similar reduction while western areas of the Humber sub-region are projected to see a reduction in annual rain fall of approximately 5.8%.

Considerable changes in seasonal rainfall are projected for both summer and winter periods. Winter average rainfall is expected to increase by 17.2% compared to the reduction in rainfall of 24.4% during the summer months. Both spring and autumn are projected to experience a small reduction in rainfall.

Severe Rainfall and Rainfall Accumulations
The Humber sub-region is projected to experience an increase in the amount of rain falling during 50% Annual Exceedance Probability (AEP) rainfall events, especially those with durations of 1 and 2 days. The 5-day duration event do not shown any change in rainfall delivered, whilst the 10-day event has a small reduction of 0.1%.

The amount of rainfall associated with 5% AEP rainfall events will increase over all the durations.  The effects will be greater for the 2-day and 5-day events with a relative change of 1.6% and 1.4% respectively.

Sub-daily 50% AEP extreme rainfall events are projected to have a reduction in total rainfall over 1-hour and 3-hour duration events, but subsequent increases over the 6-hour and 12-hour rainfall events. Rainfall over a 12-hour extreme 10% AEP event is set to increase be 10.1%.

Dry Spells
EARWIG simulations project an increase in the number of dry spells within the Humber sub-region. The number of dry spells of 10 days with less than 0.2mm and 1mm rainfall will range from 2.2 to 2.7.  The absolute change of dry spells for 20 consecutive days with less than 0.2mm and 1mm rainfall are both to increase by 0.7 days.

Snowfall
The number of days on which the Humber sub-region will expect snowfall will see a reduction both annually and seasonally.  There will be an annual average reduction of 67.6% in this sub-region.  The change will be most noticeable during the winter where a decrease of 1.6 days is expected.

There is also projected to be a decrease in the amount of snow falling over the Humber (measured in water depth equivalent). It is expected that snowfall will reduce from 10.3mm to 7mm by the 2050s, with the vast majority of the remaining snow falling in the winter.

Frost
EARWIG projects that there will be 21.4 fewer frost days per year in the 2050s than at present. This figure represents an almost 50% reduction from the present.

Wind
The annual average wind speed is set to be reduced by 0.9%.  A slight increase is projected in the winter months at 0.8% (0.1m/s) and a relative decrease in summer at
-2.9% (-0.1m/s).

Humidity and Vapour Pressure
Relative humidity on the coastal plain of the Humber sub-region is projected to decrease from 0.8 to 0.7, a relative change of -11.1%. The highest values are predicted to be experienced in the summer and the lowest in the winter.

Similarly, vapour pressure decreases from 9.9 to 9.8 at a relative change of -0.2%. Only the winter months is predicted to record an increase in this parameter. The greatest decrease is to be in summer of -0.5% relative change.

SOUTH YORKSHIRE

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Annual and Seasonal Temperature
Annual average daily mean temperatures are projected to increase by 1.9 ºC in the South Yorkshire region.

Winter and spring daily mean temperatures are projected to rise by 1.5 ºC to 1.6 ºC respectively.  Summer temperature increases are predicted to be 1 ºC greater with an increase of 2.5 ºC with a 2.2 ºC rise expected during the autumn.

Annual and Seasonal Maximum and Minimum Temperatures
Average maximum daily annual (and summer) temperatures are expected to increase by 3.1 ºC across the whole sub-region, with the greatest actual values reaching 31.0 ºC in Sheffield.  It is likely that western, higher elevation areas of the sub-region will experience changes in temperature similar to upland areas further north where values increase by 2.7 ºC.

Winter daily average maximum temperatures are expected to increase by approximately 1.3 ºC in Sheffield, which is 0.1 ºC higher then in the upland areas.

Annual and seasonal average daily minimum temperatures are also projected to increase across South Yorkshire.  Annual and winter minimum temperatures are projected to increase by 1.6 ºC which will result in an annual minimum temperature just below freezing at -0.6 ºC.

Summer average minimum daily temperatures are projected to increase by approximately 2.1 ºC and autumn values by 1.9 ºC.  Western areas of South Yorkshire may experience lower increases of approximately 1.8 ºC.  These increases are likely to result in summer values of around 13.9 ºC and autumn values of approximately 4.3 ºC.

Severe Temperatures and Heat waves
Temperatures associated with the coldest (5th percentile) extreme cold events, are projected to increase throughout of all the seasons.  The increases are expected to be between 1.8 ºC and 1.9 ºC for each season.Winter temperatures are to remain sub-zero but spring and autumn temperatures will creep above zero where they were previously below in the baseline.

In comparison, the extreme (95th percentile) hot temperatures will increase by a greater value of 3.2 ºC during the summer and autumn months. Temperatures during the summer may reach the extreme temperature of 32 ºC.  During autumn, winter and spring, extreme hot temperatures are projected to increase by 2.9 ºC , 1.0 ºC and 1.9 ºC respectively. 

The number of hot days, where the maximum temperature exceeds 28 ºC is expected to increase by an average of 5.5 days per year over the South Yorkshire sub-region. This increase is primarily expected during the summer with an increase of 0.3 days expected during the autumn. The number of 2-day heat waves, where hot days occur consecutively is also projected to increase by 0.4 days annually, resulting in an average of 0.5 occurrences per year.

Annual and Seasonal Rainfall
South Yorkshire is projected to experience a decrease in the average annual rainfall by the 2050s.  Summer rainfall in projected to reduce by 25% while the winter is set to experience an increase of 14%.  It is projected that there will be a decrease in rainfall during spring and autumn by 2.8% and 6.6% respectively.

Severe Rainfall and Rainfall Accumulations
South Yorkshire is predicted to experience an increase in 50% Annual Exceedence Probability (AEP) rainfall events across all the event durations with exception to the 5-day event where no change occurs.  The greatest relative change will be over the 1-day extreme event with an increase of 2.5%.

The 5% AEP rainfall events will increase over the 1-day and 2-day durations indicating heavier short-bursts.  The 5 and 10-day period events are projected to record a decrease in rainfall.

The 50% AEP extreme events are projected to reduce over the 1, 3 and 6 hourly-recorded events.  Rainfall over a 12-hour extreme 10% AEP event is not predicted to change.

In the upland areas of this region, it is likely that the rainfall events will be similar to those in the Yorkshire Dales where increases in rainfall are more commonly projected.

Dry Spells
There is a projected increase in the number of dry spells through South Yorkshire.  The number of dry spells of 10 days with less than 0.2mm and 1mm rainfall will range from 2.3 to 2.7 occurrences per year. The absolute change of dry spell events for 20 consecutive days with less than 0.2mm and 1mm rainfall are both predicted to increase by 0.7 and 0.8 days.

Snowfall
Change in the average number of days on which snowfall is expected to fall in South Yorkshire is greatest in winter, with a loss of 2.6 days during the winter.  Autumn is projected to receive the smallest change, with a loss of 0.3 days each autumn. The annual average snowfall record results in a loss of 3.3 days. This loss in the number of snowfall days is reflected by the reduction in the average amount of snowfall per year (measured in water equivalent). A loss of 10.4mm is projected to be seen in winter months December to February and an overall annual average reduction of 13.1mm compared to the present day values.

Frost
South Yorkshire has a projected reduction in the number of frost days from 60.4 to 35. This is a predicted relative change of -42% and is the largest reduction in frost days predicted for the lowland areas of the entire study area. However, the area to the west of this sub-region may experience similar conditions to the upland areas of the study area where the reduction is less significant.

Wind
Annual average wind speed is predicted to reduce by 0.9% across South Yorkshire. South Yorkshire sees the greatest seasonal variability across the study region with projected increases of 1% (0.1m/s) during the winter and changes in summer of -2.8% (-0.1m/s).

Humidity and Vapour Pressure
Annual average records of relative humidity in South Yorkshire show the greatest projected decrease in whole of the study region, with a projected reduction of 11.6%. This is reflected in the seasonal results with each season reflecting the greatest decrease for the parameter. The greatest actual change is only of -0.1 during each season which translates to a relative decrease of -15.1%.

It appears that the mean of the average annual vapour pressure does not differ between the present day and the 2050’s. There is projected to be a relative change of just -0.2%, which demonstrates a minimal change.  Winter is projected to receive a minimal increase in vapour pressure while the greatest change will be seen in the summer with a relative change of -0.5%.

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