Climate Change Chart of Honolulu, USA

Overview of climate changes

Temperature changes

The mean difference in monthly mean temperature, averaged across calendar months, was an increase of +0.85 °C compared with the earlier reference period. This is an unweighted average of the calendar-month means, not a day-weighted annual average, and describes the periods’ overall monthly means rather than a change in daytime maximum temperatures. The largest monthly increase was in September, with a difference of +1.10 °C. This identifies the strongest monthly increase among the reported temperature differences; it does not mean every month increased by the same amount.

Changes in rainfall

Mean daily rainfall, averaged across calendar months, had a difference of -0.37 mm/day compared with the earlier reference period. This is an unweighted mean of monthly daily-rainfall averages, not a day-weighted annual figure or a monthly rainfall total. The largest monthly decrease in mean daily rainfall was in January, a difference of -2.06 mm/day. By contrast, March had the largest monthly increase, with a difference of +0.20 mm/day. These are daily-mean differences for the named months, not changes in monthly totals, and they show that the period comparison was not uniform across the calendar.

Changes in sunshine duration

Mean daily sunshine duration, averaged across calendar months, showed a difference of -0.22 hours/day between the reference periods. The figure describes an unweighted average of monthly daily means; it should not be read as a day-weighted annual total or as a change applying equally to every month. The largest monthly decrease in mean daily sunshine was in March, with a difference of -0.49 hours/day. The largest monthly increase occurred in January, with a difference of +0.16 hours/day. Together, these month-specific differences indicate contrasting changes across the calendar rather than a uniform shift in daily sunshine.