Climate Change Chart of Stevens Pass, USA

Overview of climate changes

Temperature changes

Monthly mean temperatures were higher by a mean difference of +1.57 °C averaged across calendar months; this is an unweighted comparison of monthly means, not a day-weighted annual average or a measure of daytime maximum temperatures. The largest monthly increase was in January, with a difference of +3.77 °C. This identifies the strongest reported monthly increase, rather than implying that every month changed by the same amount.

Changes in snowfall

Mean daily snowfall had a mean difference of -0.17 mm/day averaged across calendar months. This is an unweighted comparison of monthly means, not a day-weighted annual average, and the small aggregate difference does not mean snowfall was absent. The largest monthly increase was in January, with a difference of +7.97 mm/day; the largest monthly decrease was in November, with a difference of -5.86 mm/day. These contrasting monthly differences help explain why the mean across calendar months is comparatively small.

Changes in rainfall

Mean daily rainfall increased by a mean difference of +0.56 mm/day averaged across calendar months. This is an unweighted comparison of monthly means, not a day-weighted annual average, and the figures describe daily means rather than monthly totals. The largest monthly increase occurred in November, with a difference of +1.64 mm/day. In contrast, July / August had the largest monthly decrease, a difference of -0.23 mm/day; that decrease is limited to the reported monthly comparison and does not overturn the mean increase across calendar months.

Changes in sunshine duration

Mean daily sunshine duration showed a mean difference of -0.37 hours/day averaged across calendar months, indicating lower monthly mean sunshine in the more recent period. This unweighted summary does not establish the same change for every month. The largest monthly decrease was in January, with a difference of -0.79 hours/day. The largest monthly increase was in June, at a difference of +0.09 hours/day, showing that the overall mean decrease coexists with a reported monthly increase.