Climate Change Chart of Barcelona, Spain

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.22 °C compared with the earlier reference period. This is an unweighted mean of the monthly means, not a day-weighted annual average, and it describes the aggregate rather than implying the same change in every month. The largest monthly increase was in December, with a difference of +2.03 °C; these are monthly mean temperatures, not daytime maximum temperatures.

Changes in rainfall

Across calendar months, mean daily rainfall had an unweighted mean difference of +0.25 mm/day compared with the earlier period. This summarizes monthly means rather than monthly rainfall totals, and does not mean that rainfall increased in every month. The largest monthly increase was in October, at a difference of +1.05 mm/day, while the largest monthly decrease was in December, at a difference of -0.90 mm/day. These contrasting monthly differences show why the aggregate mean should not be read as a uniform month-by-month change.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.14 hours/day in the more recent period. This is an unweighted average of monthly means, not a day-weighted annual figure or a claim that every month changed in the same direction. The largest monthly increase occurred in January, with a difference of +0.44 hours/day; the largest decrease occurred in September, with a difference of -0.55 hours/day. The monthly extremes therefore provide useful context for the overall mean difference without describing daily conditions.

Changes in snowfall

Mean daily snowfall, averaged across calendar months, had a difference of -0.20 mm/day compared with the earlier reference period. This unweighted monthly-mean comparison is not a measure of monthly snowfall totals, and its aggregate does not imply an identical change in every month. The largest monthly decrease was in January, with a difference of -1.55 mm/day; the largest monthly increase was in April, with a difference of +0.01 mm/day. These recorded differences describe the supplied snowfall measurements, rather than establishing that snowfall was absent in any period.