Climate Change Chart of Providence, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.72 °C compared with the earlier reference 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 December, at a difference of +2.12 °C, while November had the largest monthly decrease, with a difference of -0.53 °C.

Changes in rainfall

For mean daily rainfall, the unweighted difference averaged across calendar months was +0.48 mm/day in the more recent period; this describes monthly means rather than monthly rainfall totals. The strongest monthly increase was in December, with a difference of +1.34 mm/day, whereas November recorded the largest decrease, a difference of -0.85 mm/day. These monthly contrasts show that the mean change across months does not describe the change in every individual month.

Changes in sunshine duration

Mean daily sunshine duration had an unweighted difference across calendar-month means of -0.24 hours/day compared with the earlier reference period; this is not a day-weighted annual average. The monthly pattern was not uniform: May had the largest increase, with a difference of +0.64 hours/day, while October had the largest decrease, with a difference of -0.87 hours/day.

Changes in snowfall

Mean daily snowfall averaged across calendar months had a difference of +0.08 mm/day in the more recent period. This unweighted mean of monthly means is distinct from a day-weighted annual average. Monthly differences varied in direction: the largest increase was in March, at a difference of +2.13 mm/day, while the largest decrease was in January, at a difference of -1.26 mm/day. The average across months therefore does not imply the same change in each month.