Climate Change Chart of Valley of Isere, France

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +2.67 °C compared with the earlier reference period. This is an unweighted mean of monthly means, not a day-weighted annual average, and it describes mean temperatures rather than daytime maximum temperatures. The largest monthly increase in mean temperature occurred in December, with a difference of +7.13 °C; this identifies the strongest monthly increase, not a change shared by every month.

Changes in snowfall

Averaged across calendar months, mean daily snowfall increased by +5.05 mm/day compared with the earlier reference period. This is an unweighted mean of monthly means, not a day-weighted annual average, and it describes daily mean amounts rather than monthly totals. The largest monthly increase in mean daily snowfall occurred in March, with a difference of +16.42 mm/day. The largest decrease was in June, at -2.99 mm/day, showing that the monthly differences did not all move in the same direction.

Changes in rainfall

Averaged across calendar months, mean daily rainfall increased by +0.20 mm/day compared with the earlier reference period. This unweighted mean of monthly means is not a day-weighted annual average, and the measure is a daily mean rather than a monthly total. The largest monthly increase was in October, at a difference of +0.94 mm/day in mean daily rainfall. In contrast, November had the largest monthly decrease, with a difference of -0.28 mm/day; these are month-specific differences, not monthly rainfall totals.

Changes in sunshine duration

Averaged across calendar months, mean daily sunshine duration had a difference of -0.26 hours/day, indicating a lower mean in the more recent period. This is an unweighted average of monthly means, not a day-weighted annual average. Monthly differences varied in direction: March had the largest decrease, at -0.80 hours/day, while June had the largest increase, at +0.45 hours/day. These describe average daily sunshine hours in the named months, not every day within them.