Climate Change Chart of Lyon, France

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.76 °C compared with the earlier reference period; this is an unweighted mean of the month-by-month averages, not a day-weighted annual average or a measure of daytime maximum temperatures. The largest monthly increase was in January, with a difference of +3.51 °C. That identifies the strongest increase among the monthly mean-temperature differences, rather than describing every month.

Changes in rainfall

Mean daily rainfall, averaged across calendar months, had a difference of +0.18 mm/day compared with the earlier reference period. This is an unweighted average of monthly means, not an annual total or a day-weighted average. The monthly differences point in different directions: September had the largest decrease, with a difference of -1.04 mm/day, while October had the largest increase, with a difference of +0.85 mm/day. These are changes in mean daily amounts, not monthly rainfall totals.

Changes in snowfall

Averaged across calendar months, mean daily snowfall had a difference of -0.37 mm/day compared with the earlier reference period. This unweighted mean of monthly differences is not a snowfall total, and does not mean that snowfall was absent in either period. Monthly snowfall differences were not uniform: the largest decrease was in February, with a difference of -2.12 mm/day, while the largest increase was in November, with a difference of +0.81 mm/day. These describe mean daily amounts for those months, not monthly totals.

Changes in sunshine duration

Averaged across calendar months, mean daily sunshine duration had a difference of -0.35 hours/day compared with the earlier reference period; this is an unweighted average of monthly means, rather than a day-weighted annual figure. The largest monthly decrease was in October, with a difference of -0.77 hours/day, whereas the largest increase was in February, with a difference of +0.26 hours/day. These extremes show how monthly differences varied, without implying that every month changed in the same direction.