Climate Change Chart of San Diego, USA

Overview of climate changes

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, averaged across calendar months shows a difference of -0.14 mm/day compared with the earlier reference period. The monthly pattern was not uniform: February had the largest decrease, a difference of -1.03 mm/day, while May recorded the largest increase, a difference of +0.33 mm/day. These monthly contrasts show why the overall mean difference should not be read as a change applying equally to each month.

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.01 °C compared with the earlier reference period; this is an unweighted mean of 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 +1.53 °C. That identifies the strongest increase among the supplied monthly comparisons, rather than describing every month's change.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.67 hours/day compared with the earlier reference period; this unweighted summary of monthly means is not a day-weighted annual total. The largest monthly decrease was shared by May / June, with a difference of -1.32 hours/day. The tied months therefore mark the clearest monthly reductions in the supplied comparisons, without implying that every month changed by the same amount.

Changes in snowfall

Mean daily snowfall averaged across calendar months had an unchanged difference at the displayed precision, 0.00 mm/day. This rounded summary does not establish that snowfall was absent or that there was no variation beyond the displayed precision. The largest monthly decrease was in January, with a difference of -0.05 mm/day; this daily-mean measure is not a monthly snowfall total.