Climate Change Chart of Oahu (Hawaii), USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +0.68 °C compared with the earlier reference period. This is an unweighted mean of the monthly means, rather than a day-weighted annual average, and describes the aggregate comparison rather than every month; it also refers to mean temperature, not daytime maximums. The largest monthly increase in mean temperature was in September, with a difference of +0.96 °C. That identifies the strongest monthly increase, not a uniform change across the year or a continuous trend between the reference periods.

Changes in rainfall

Averaged across calendar months, mean daily rainfall had a difference of -0.10 mm/day compared with the earlier period. This unweighted mean of monthly means summarizes daily rainfall amounts across the calendar months; it is not a monthly total and does not imply that rainfall decreased in every month. Monthly differences varied in direction: January had the largest decrease, a difference of -1.93 mm/day, while March had the largest increase, a difference of +0.70 mm/day. These are monthly mean daily amounts, not accumulated monthly rainfall.

Changes in sunshine duration

Mean daily sunshine duration, averaged across calendar months, had a difference of -0.28 hours/day. This unweighted aggregate of monthly means does not indicate the same difference in every month or describe a continuous trend between the reference periods. The largest monthly decrease in mean daily sunshine was in March, with a difference of -0.60 hours/day; the largest increase was in January, with a difference of +0.10 hours/day. These month-specific comparisons show that the direction of the difference was not uniform across the year.