Climate Change Chart of Calgary, Canada

Overview of climate changes

Temperature changes

Averaged across calendar months, the difference in monthly mean temperature was +1.52 °C compared with the earlier reference period; 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 +5.14 °C. By contrast, October had the largest monthly decrease, a difference of -0.11 °C. These monthly extremes show that the overall mean difference did not apply uniformly across the calendar.

Changes in snowfall

Mean daily snowfall showed an unweighted difference across calendar-month means of +0.50 mm/day in the more recent period; these are daily averages, not monthly snowfall totals. The largest monthly increase was in December, with a difference of +2.59 mm/day, while May had the largest decrease, at a difference of -0.85 mm/day. The mean summarizes the month-by-month period averages and does not imply that snowfall changed in the same direction in every month or on every day.

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, had an unweighted difference across calendar-month means of -0.03 mm/day in the more recent period. The largest monthly decrease occurred in May, with a difference of -0.65 mm/day, while August recorded the largest increase, a difference of +0.40 mm/day. These are differences between period averages for the named months; they do not describe every day's rainfall or establish a continuous change between the reference periods.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.32 hours/day compared with the earlier reference period; this unweighted monthly-mean comparison is not a day-weighted annual average. The largest monthly decrease was in April, at a difference of -0.63 hours/day, whereas June had the largest increase, a difference of +0.41 hours/day. The overall difference therefore summarizes monthly averages and should not be read as the change in sunshine for every month or day.