Climate Change Chart of Big Sky Ski-Resort, USA

Overview of climate changes

Changes in snowfall

Mean daily snowfall increased by +1.12 mm/day when the monthly means are averaged across calendar months; this unweighted summary is not a day-weighted annual average or a monthly total. The largest monthly increase was in December, at a difference of +3.51 mm/day. By contrast, November had the largest monthly decrease, a difference of -0.16 mm/day. These period averages describe a broad monthly pattern and do not establish that the same change occurred in every month.

Temperature changes

The unweighted mean difference across calendar-month mean temperatures is an increase of +1.73 °C; this summarizes monthly means rather than daytime maximum temperatures and does not imply the same change in every month. The largest monthly increase was in January, at a difference of +5.24 °C. In contrast, October had the largest monthly decrease, a difference of -0.29 °C.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months decreased by -0.51 hours/day. The largest monthly reduction was in April, where the difference was -0.85 hours/day; June went the other way, with the largest monthly increase of +0.21 hours/day. These are differences in monthly mean daily hours, not statements about every day or every month.

Changes in rainfall

Averaged across calendar months, mean daily rainfall increased by +0.16 mm/day. This is an unweighted comparison of monthly means, not a day-weighted annual average or a monthly total. The largest monthly increase occurred in August, with a difference of +0.80 mm/day, while June recorded the largest decrease, a difference of -0.58 mm/day. These monthly contrasts show why the overall mean should not be read as a uniform change through the year.