Climate Change Chart of Rottnest Island, Australia

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature showed a difference of +0.50 °C in the more recent period. This is an unweighted comparison of monthly means, not a day-weighted annual average, and it describes the overall average difference rather than a change present in every month. The largest monthly increase was in July, with a difference of +1.99 °C compared with the earlier reference period. By contrast, February had the largest monthly decrease, a difference of -1.26 °C. These are monthly mean temperatures, not daytime maximum temperatures; the two selected months illustrate differing changes rather than a continuous pattern through the year.

Changes in rainfall

The mean daily rainfall difference averaged across calendar months was 0.00 mm/day in the more recent period. This unchanged value at the displayed precision applies to the unweighted mean of the calendar-month means; it does not mean that rainfall was unchanged in each month or that there was no change beyond the displayed precision. Monthly differences varied: May recorded the largest increase, a difference of +0.71 mm/day, while July recorded the largest decrease, a difference of -1.18 mm/day compared with the earlier reference period. These figures describe mean daily rainfall, not monthly totals, so they should not be read as the amount of rain accumulated over either month.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.14 hours/day in the more recent period. This is an unweighted average of monthly means, not a day-weighted annual figure, and does not imply that sunshine duration decreased in every month. The monthly differences were not uniform: the largest increase occurred in June, at a difference of +0.33 hours/day, while the largest decrease was in March, at a difference of -0.60 hours/day compared with the earlier reference period. The values refer to mean daily sunshine hours, rather than total hours across each month.