Climate Change Chart of Olympia, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.37 °C compared with the earlier reference period; this is an unweighted mean of monthly averages, not a day-weighted annual figure. The largest monthly increase was in January, with a difference of +1.89 °C, while December had the largest decrease, at -0.58 °C. These are changes in monthly mean temperature, not daytime highs, and do not imply that every month followed the same pattern.

Changes in rainfall

For mean daily rainfall, the unweighted average of the calendar-month means had a difference of +0.09 mm/day. The largest increase was in January, at +1.89 mm/day, whereas February recorded the largest decrease, with a difference of -0.78 mm/day. These figures describe average daily amounts, not monthly rainfall totals or the number of rainy days, and the aggregate change does not mean rainfall rose in every month.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.32 hours/day. The largest monthly decline occurred in September, with a difference of -0.90 hours/day, while June had the largest increase, at +0.31 hours/day. These shifts in daily averages describe reference-period comparisons, not the sunshine visitors can expect on any particular day.