Climate Change Chart of Olympia, USA

Overview of climate changes

Changes in snowfall

Mean daily snowfall averaged across calendar months had a difference of -0.23 mm/day in the more recent period. This unweighted mean describes the aggregate of monthly averages, not an annual snowfall total, and does not mean the same difference applied in every month. The clearest monthly contrasts were in January, where the largest decrease was a difference of -4.43 mm/day, and February, where the largest increase was a difference of +1.21 mm/day. These are differences in mean daily snowfall, not monthly totals.

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.37 °C compared with the earlier reference period; this unweighted mean summarizes the month-by-month averages, rather than a day-weighted annual value or daytime maximum temperatures. The largest monthly increase was in January, with a difference of +1.89 °C. By contrast, December had the largest monthly decrease, a difference of -0.58 °C; these monthly extremes show that the changes were not uniform across the calendar.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.32 hours/day compared with the earlier reference period. This unweighted summary of monthly means describes an aggregate across the calendar, not a uniform change in daily sunshine in every month. The largest monthly increase was in June, with a difference of +0.31 hours/day, while September recorded the largest monthly decrease, a difference of -0.90 hours/day. These monthly contrasts put the overall mean difference in context without implying a continuous trend between the reference periods.

Changes in rainfall

Mean daily rainfall averaged across calendar months had a difference of +0.09 mm/day in the more recent period. This is an unweighted mean of monthly averages, not an annual total or a day-weighted annual average, and it does not imply the same difference in every month. The largest monthly increase in mean daily rainfall occurred in January, with a difference of +1.89 mm/day; the largest monthly decrease was in February, at a difference of -0.78 mm/day. These are daily mean amounts, not monthly rainfall totals.