Climate Change Chart of Lisbon, Portugal

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.70 °C compared with the earlier reference period; this unweighted average describes the set of monthly means, not a day-weighted annual average or daytime maximum temperatures. The largest monthly increase was in May, with a difference of +1.68 °C. In contrast, November had the largest monthly decrease, a difference of -0.17 °C.

Changes in sunshine duration

Across calendar months, mean daily sunshine duration had a difference of -0.27 hours/day compared with the earlier reference period. This unweighted mean of monthly means summarizes the overall comparison, rather than indicating the same change in every month. Monthly differences varied: April had the largest decrease, at -0.67 hours/day, while December recorded the largest increase, a difference of +0.09 hours/day.

Changes in rainfall

Averaged across calendar months, mean daily rainfall had a difference of -0.04 mm/day; this is an unweighted comparison of monthly means, not a change in monthly totals or a day-weighted annual average. The largest monthly increase in mean daily rainfall occurred in October, with a difference of +0.68 mm/day. The largest decrease was in January, at a difference of -1.10 mm/day.

Changes in snowfall

Averaged across calendar months, mean daily snowfall had a difference of -0.02 mm/day. This is an unweighted average of monthly means, not a monthly total; the small average difference does not imply that snowfall was absent. The largest monthly decrease in mean daily snowfall was in January, with a difference of -0.22 mm/day. This monthly comparison describes an average daily amount, not a monthly snowfall total.