Climate Change Chart of Wellington, New Zealand

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.51 °C. This is an unweighted average of monthly means, rather than a day-weighted annual figure, and describes the comparison between the reference periods rather than a continuous trend. The largest monthly increase was in June, with a difference of +2.40 °C; monthly means describe average conditions, not daytime maximum temperatures.

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, averaged across calendar months shows a difference of +0.36 mm/day in the more recent period. This unweighted mean summarizes the monthly comparisons and does not mean that rainfall increased in every month. The largest monthly increase occurred in April, at a difference of +1.04 mm/day, while January had the largest decrease, a difference of -0.57 mm/day. These month-specific differences show that the overall average combines changes in opposite directions.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.58 hours/day compared with the earlier reference period. This is an unweighted average of monthly mean daily hours, not a day-weighted annual total, and it does not imply the same change in every month. The largest monthly decrease was in September, with a difference of -1.10 hours/day. This marks the strongest monthly reduction in the supplied comparison, not a description of sunshine on every day in that month.

Changes in snowfall

Mean daily snowfall averaged across calendar months shows a difference of +0.01 mm/day in the more recent period. This small average difference summarizes monthly means; it does not establish that snowfall changed in the same way in every month. The largest monthly increases occurred in June / August, each with a difference of +0.03 mm/day, while the largest decrease was in July, at a difference of -0.01 mm/day. These daily mean amounts are not monthly totals, and the comparison does not imply snowfall was absent in either period.