Climate Change Chart of Phoenix, USA

Overview of climate changes

Temperature changes

Monthly mean temperature was higher by a difference of +1.86 °C averaged across calendar months in the more recent period; this is an unweighted comparison of monthly means, not a day-weighted annual average or a measure of daytime maximum temperatures. The largest monthly increase was in March, with a difference of +3.08 °C compared with the earlier reference period, so that month marks the strongest reported monthly rise rather than a description of every month.

Changes in rainfall

Mean daily rainfall increased by a difference of +0.26 mm/day averaged across calendar months in the more recent period. This unweighted mean summarizes monthly averages; it is not a monthly rainfall total or a day-weighted annual average. The largest monthly increase was in July, at a difference of +1.34 mm/day, while April had the largest monthly decrease, a difference of -0.25 mm/day. These monthly contrasts show that the overall mean does not describe the change in every individual month.

Changes in sunshine duration

Mean daily sunshine duration was lower by a difference of -0.22 hours/day averaged across calendar months in the more recent period; this is an unweighted average of monthly means, not a day-weighted annual figure. The largest monthly decrease was in July, with a difference of -0.75 hours/day. By contrast, April recorded the largest monthly increase, a difference of +0.08 hours/day. These are changes in monthly mean daily hours, so neither the overall average nor either monthly extreme implies the same change in every month.

Changes in snowfall

Mean daily snowfall was lower by a difference of -0.01 mm/day averaged across calendar months. This small aggregate difference describes the unweighted comparison of monthly means, not a day-weighted annual average, and should be read at the displayed precision rather than as evidence of no change. The largest monthly decrease was in December, with a difference of -0.06 mm/day; this identifies the strongest reported monthly decrease, not a change shared by every month.