Climate Change Chart of Niseko, Japan

Overview of climate changes

Changes in snowfall

Mean daily snowfall, not monthly snowfall totals, averaged across calendar months had a difference of +2.01 mm/day in the more recent period. The mean is unweighted across monthly averages and does not indicate that snowfall changed by the same amount in each month. The largest monthly increase was in January, with a difference of +8.30 mm/day in mean daily snowfall. In April, the largest monthly decrease was a difference of -1.32 mm/day, so the average across months should not be read as a uniform monthly change.

Changes in sunshine duration

Averaged across calendar months, mean daily sunshine duration had a difference of -0.87 hours/day compared with the earlier reference period. This is an unweighted mean across monthly averages, not a day-weighted annual figure. The largest monthly decrease occurred in August, with a difference of -1.60 hours/day in mean daily sunshine duration. The largest monthly increase was much more limited in July, at a difference of +0.13 hours/day; these month-specific results qualify the across-month mean.

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.13 °C compared with the earlier reference period; this is an unweighted mean of monthly means, not a day-weighted annual average or a measure of daytime highs. The largest monthly increase was in May, with a difference of +2.52 °C. By contrast, August had the largest monthly decrease, a difference of -0.39 °C; these are month-specific differences between reference periods, not evidence of a continuous trend.

Changes in rainfall

Mean daily rainfall, rather than monthly totals, averaged across calendar months shows a difference of +0.66 mm/day in the more recent period. This unweighted mean summarizes the differences among monthly means and does not imply that rainfall increased in every month. The largest monthly increase was in August, where mean daily rainfall had a difference of +3.02 mm/day. In September, the largest monthly decrease was a difference of -0.91 mm/day, showing that the overall mean does not describe every month's change.