Climate Change Chart of Des Moines, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, the difference in monthly mean temperature was +1.44 °C compared with the earlier reference period; this unweighted mean describes the set of monthly averages, not a day-weighted annual average or daytime maximum temperatures. The largest monthly increase was in December, with a difference of +2.58 °C. By contrast, October had the largest decrease, a difference of -0.63 °C.

Changes in snowfall

Averaged across calendar months, mean daily snowfall had a difference of -0.34 mm/day in the more recent period. This unweighted mean describes monthly daily averages, not monthly snowfall totals. The largest monthly decrease in mean daily snowfall occurred in March, with a difference of -2.74 mm/day. In May, the largest monthly increase was a difference of +0.49 mm/day; these are differences in daily averages and do not imply that snowfall was absent in either period.

Changes in rainfall

Averaged across calendar months, mean daily rainfall had a difference of +0.31 mm/day in the more recent period. This is an unweighted mean of monthly averages, not a change in monthly totals or a day-weighted annual average. The largest monthly increase in mean daily rainfall occurred in October, with a difference of +1.29 mm/day. In June, the largest monthly decrease was a difference of -0.72 mm/day; these monthly comparisons describe daily means rather than accumulated monthly rainfall.

Changes in sunshine duration

The unweighted mean difference in daily sunshine duration across calendar months was +0.01 hours/day. This summarizes the monthly averages and should not be read as a day-weighted annual average. The largest monthly increase in mean daily sunshine was in June, with a difference of +1.43 hours/day. The largest decrease occurred in May, at a difference of -0.45 hours/day.