4.2 Projected patterns of change from the Weather Generator

Ensembles of Weather Generator outputs were produced on a 25 km grid across the UK in a similar manner as for the sites. Change Factors are available on the 25 km grid, and the observed statistics were averaged from the 5 km grid resolution to match. A sample of the outputs are shown here.

The largest increase in hot days is found in the South East of England (see Figure 7), where for the 50th percentile (or median case) an increase from around 20 to more than 50 days per year is expected. The maps should be interpreted as showing the differences (increases) in frequency of hot days between the same percentile. For example, for the 90th percentile maps, they show the number of days per year which is exceeded on average in only 10% of years.

A corresponding decrease in frost days is found as shown in Figure 8. Substantial decreases are found across the UK, except where they are already close to zero (e.g. near coasts).

Finally, changes in the pattern of dry spells are shown in Figure 9, where modest increases are found across the country and substantial increases in the south and east associated with summer drying.