Climate Change Chart of Birmingham, Great Britain

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.89 °C compared with the earlier reference period; this is an unweighted comparison of monthly means, not a day-weighted annual average or a continuous trend. The largest monthly increase was in January / December, at a difference of +1.85 °C. By contrast, April had the largest monthly decrease, a difference of -0.46 °C. These are monthly mean temperatures, not daytime maxima, and the extremes do not describe every month.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.38 hours/day in the more recent period; this is an unweighted mean of monthly means, not a day-weighted annual figure. The largest monthly decrease was in June, with a difference of -1.17 hours/day. The largest increase went the other way: in February, sunshine had a difference of +0.18 hours/day. These contrasting monthly differences put the overall mean in context without implying the same change throughout the year.

Changes in rainfall

Mean daily rainfall, rather than monthly totals, was higher on average across calendar months: the unweighted mean difference was +0.54 mm/day compared with the earlier period. The largest monthly increase occurred in December, with a difference of +1.02 mm/day, while the largest monthly decrease was in April, at -0.06 mm/day. These selected monthly changes show that the average shift was not uniform across months; they do not indicate the change in every individual day or month.

Changes in snowfall

Mean daily snowfall also differed across the periods, although its unweighted mean across calendar months was close to unchanged: the difference was -0.06 mm/day. That small aggregate difference does not mean snowfall was absent or unchanged in every month. The largest monthly decrease was in January, at -2.39 mm/day, while the largest increase occurred in March, with a difference of +1.27 mm/day. These are daily mean amounts, not monthly snowfall totals.