Climate Change Chart of Sacramento, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.45 °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 overall comparison rather than a change in every month. The largest monthly increase in mean temperature was in June, with a difference of +2.36 °C. This identifies the strongest monthly increase, not daytime maximum temperatures or a continuous trend.

Changes in rainfall

Averaged across calendar months, mean daily rainfall had a difference of -0.16 mm/day compared with the earlier reference period. This unweighted average of monthly means summarizes the comparison; it does not mean rainfall declined in every month, and the measure is a daily mean rather than a monthly total. The largest monthly decrease in mean daily rainfall occurred in November, with a difference of -1.05 mm/day. By contrast, December had the largest monthly increase, with a difference of +0.40 mm/day; these opposing monthly changes show why the across-month average should not be read as a description of each month.

Changes in sunshine duration

Mean daily sunshine duration, averaged across calendar months, had a difference of -0.04 hours/day. This unweighted average summarizes the monthly means rather than a day-weighted annual average, and does not imply the same change in every month. The largest monthly decrease was in January, with a difference of -0.64 hours/day. In February, mean daily sunshine instead had the largest monthly increase, a difference of +0.56 hours/day; these are monthly mean differences, not measures of day-to-day variability.

Changes in snowfall

Mean daily snowfall averaged across calendar months had a difference of +0.01 mm/day compared with the earlier reference period. This small difference reflects the unweighted average of monthly means; it should not be taken to mean snowfall was absent or that every month changed by the same amount. The largest monthly increase in mean daily snowfall was in February, with a difference of +0.18 mm/day. The largest monthly decrease was in January, with a difference of -0.05 mm/day; both are differences in daily means, not monthly snowfall totals.