Climate Change Chart of New York City, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, the monthly mean temperature difference was +0.71 °C; this is an unweighted comparison of monthly means, not a day-weighted annual figure or a measure of daytime maximum temperatures. The largest monthly increase was in December, with a difference of +2.26 °C compared with the earlier reference period. By contrast, November had the largest monthly decrease, a difference of -0.55 °C.

Changes in rainfall

Averaged across calendar months, mean daily rainfall had a difference of +0.43 mm/day; this unweighted monthly comparison describes daily mean amounts, not monthly rainfall totals or rainfall on every individual day. The largest monthly increase occurred in October, where mean daily rainfall had a difference of +1.90 mm/day compared with the earlier reference period. In November, the largest monthly decrease was a difference of -0.76 mm/day, showing that the overall mean difference did not apply uniformly across months.

Changes in sunshine duration

Across calendar months, the unweighted mean difference in daily sunshine duration was -0.12 hours/day; this aggregate does not imply the same change in each month. The largest monthly increase was in July, with a difference of +0.88 hours/day in mean daily sunshine compared with the earlier reference period. The largest decrease was in February, where mean daily sunshine had a difference of -0.77 hours/day.

Changes in snowfall

The unweighted mean difference in mean daily snowfall, averaged across calendar months, was +0.26 mm/day. These are daily mean amounts rather than monthly totals, and the aggregate does not describe every month individually. The largest monthly increase was in March, with mean daily snowfall showing a difference of +2.75 mm/day compared with the earlier reference period. In January, the largest monthly decrease was a difference of -0.96 mm/day; the differing monthly directions sit alongside the overall mean difference rather than contradicting it.