Climate Change Chart of Harrisburg, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.88 °C; this is an unweighted comparison of monthly means, not a day-weighted annual average or a description of daytime maximum temperatures. The monthly differences were not uniform: December had the largest increase, a difference of +2.13 °C, while November had the largest decrease, a difference of -0.36 °C. These extrema describe specific months, rather than a continuous change between the reference periods.

Changes in snowfall

Mean daily snowfall averaged across calendar months shows a difference of -0.18 mm/day. This unweighted mean of monthly values is not a day-weighted annual average or a monthly snowfall total. The largest monthly increase occurred in November, with a difference of +0.76 mm/day, while the largest decrease occurred in January, with a difference of -1.87 mm/day. These contrasting monthly changes show why the mean difference should not be taken to describe every month’s snowfall.

Changes in rainfall

Mean daily rainfall averaged across calendar months shows a difference of +0.08 mm/day in the more recent period; this unweighted mean of monthly values is not a day-weighted annual average, and it should not be read as a change in monthly rainfall totals. Monthly differences varied: September recorded the largest increase, a difference of +1.00 mm/day, whereas May recorded the largest decrease, a difference of -1.16 mm/day. Those monthly contrasts help qualify the small overall mean difference without implying that every month followed the same pattern.

Changes in sunshine duration

Mean daily sunshine duration, averaged across calendar months, shows a difference of -0.15 hours/day. This is an unweighted comparison of monthly means rather than a day-weighted annual average, and it does not indicate that daily sunshine changed by the same amount in every month. The largest monthly increase was in July, with a difference of +0.44 hours/day; the largest decrease was in February, with a difference of -0.78 hours/day. Together, these differences show that the overall mean masks contrasting monthly changes, not a uniform shift across the calendar.