Climate Change Chart of Juneau, Alaska, USA

Overview of climate changes

Changes in snowfall

Mean daily snowfall averaged across calendar months had a difference of +6.52 mm/day compared with the earlier reference period. This unweighted mean summarizes monthly means, not monthly totals, and the reported difference indicates a change in recorded snowfall without specifying conditions on every day or in every month. The largest monthly increase was in February, where mean daily snowfall had a difference of +21.03 mm/day. The largest monthly decrease occurred in May, with a difference of -0.34 mm/day, illustrating that the across-month mean does not apply uniformly throughout the year.

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.64 °C in the more recent period. This is an unweighted mean of monthly means, not a day-weighted annual average or a statement about every month; monthly means also should not be read as daytime maximum temperatures. The largest monthly increase was in June, with a difference of +2.81 °C. By contrast, March had the largest monthly decrease, a difference of -1.50 °C. These contrasting monthly results show why the mean difference does not describe each month's change.

Changes in rainfall

Mean daily rainfall, averaged across calendar months, had a difference of +1.05 mm/day compared with the earlier reference period. This summarizes monthly mean daily amounts without weighting months by their number of days, and it is not a monthly rainfall total or a description of every month's conditions. The largest monthly increase was in August, where mean daily rainfall had a difference of +4.31 mm/day. In March, the largest monthly decrease was a difference of -0.65 mm/day, so the overall mean does not imply that rainfall increased in every month.

Changes in sunshine duration

Averaged across calendar months, mean daily sunshine duration had a difference of +0.02 hours/day in the more recent period. This is an unweighted average of monthly means, rather than a day-weighted annual measure, and the small displayed difference should be understood at the precision shown. The largest monthly increase occurred in July, with a difference of +0.83 hours/day hours per day. In June, sunshine instead had the largest monthly decrease, a difference of -0.63 hours/day; these month-specific changes need not match the mean across calendar months.