Climate Change Chart of Banff, Canada

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature showed a difference of +1.00 °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 highs. The monthly pattern was not uniform: January had the largest increase, a difference of +3.36 °C, while December had the largest decrease, a difference of -0.79 °C. These extrema describe the strongest monthly changes in opposite directions, rather than conditions in every month.

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, was lower on average across calendar months, with a difference of -0.26 mm/day. The month-to-month changes varied: July recorded the largest decrease, a difference of -1.11 mm/day, whereas November had the largest increase, a difference of +0.07 mm/day. The mean describes the aggregate of the calendar-month means and does not imply that daily rainfall fell in every month.

Changes in snowfall

Mean daily snowfall, not monthly snowfall totals, increased on average across calendar months, with a difference of +0.31 mm/day. That aggregate does not mean snowfall rose in every month: December had the largest increase, a difference of +3.60 mm/day, while May had the largest decrease, a difference of -3.20 mm/day. The average and monthly extrema describe distinct aspects of the comparison, and do not indicate that snowfall was absent in other months.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.24 hours/day compared with the earlier period; this unweighted mean is not a day-weighted annual figure. The monthly extremes went in different directions: June had the largest increase, a difference of +0.47 hours/day, while December had the largest decrease, a difference of -0.70 hours/day. These monthly differences show why the overall average should not be read as a change applying equally throughout the year.