Climate Change Chart of Bologna, Italy

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.62 °C in the more recent period; this is an unweighted comparison of the monthly means, not a day-weighted annual average or a measure of daytime highs. The largest monthly increase was in January, with a difference of +3.57 °C compared with the earlier reference period. In contrast, September had the largest decrease, a difference of -0.16 °C. These month-specific differences describe changes in monthly averages, not every individual day's temperature.

Changes in snowfall

Mean daily snowfall had an unweighted difference across calendar-month means of -0.89 mm/day compared with the earlier reference period. The largest monthly decrease was in January, with a difference of -7.83 mm/day; by contrast, March recorded the largest increase, a difference of +0.11 mm/day. These values concern average daily snowfall, not monthly totals, and the comparison does not imply snowfall was absent in either period.

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, had an unweighted difference across calendar-month means of +0.39 mm/day compared with the earlier reference period. The monthly pattern was not uniform: May recorded the largest increase, a difference of +1.69 mm/day, while October had the largest decrease, a difference of -1.08 mm/day. These figures describe average daily amounts within the respective months, not how much rain fell in a whole month or the rainfall on any particular day.

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 unweighted mean summarizes monthly averages rather than a day-weighted annual figure. The largest monthly increase occurred in January, at a difference of +0.38 hours/day, whereas May saw the largest decrease, a difference of -0.50 hours/day. These are shifts in average daily sunshine for those months, not a description of every day.