Climate averages 1991–2020

Honolulu weather
in September.

A warm, very dry month: the warmest and the 4th driest of the year. Meets the pleasant-weather rule

Long-term climate patterns, not a forecast for a particular trip.

Average high 27.8°C Daytime mean, September

Average low 24.5°C Night-time mean, September

Rainfall 10 mm 2 days with ≥1 mm

Daylight 12 h Sunrise to sunset, per day

September is a warm month in Honolulu: daytime highs average 27.8°C and nights cool to about 24.5°C. By daytime temperature it is the warmest month of the year.

Expect about 10 mm of rain on roughly 2 days, which makes September a very dry month (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 17 min on an average September day.

Among the 498 cities listed in the United States, Honolulu ranks joint 211th of 498 for the warmest September highs and joint 112th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Honolulu is 0.9°C warmer than that mean.

From September to October, average highs fall by 0.5°C to 27.3°C, and monthly rainfall rises from 10 mm to 20 mm.

The annual picture

September in context

30-year average

Average highAverage low°C

Monthly rainfall

Average total · mm

Averages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated

Every month, side by side

Honolulu climate table

1991–2020

Monthly climate averages for Honolulu, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January	24.3°C21.3°C	21.3°C	37	4.9	11.011 h
February	24.1°C21.0°C	21.0°C	29	4.5	11.411 h
March	24.3°C21.2°C	21.2°C	39	4.4	12.012 h
April	25.0°C21.9°C	21.9°C	11	2.4	12.613 h
May	26.0°C22.7°C	22.7°C	13	2.2	13.113 h
June	26.8°C23.6°C	23.6°C	8.0	1.1	13.413 h
July	27.3°C24.1°C	24.1°C	5.9	1.0	13.313 h
August	27.7°C24.5°C	24.5°C	9.9	1.8	12.913 h
September, selected	27.8°C24.5°C	24.5°C	10	2.2	12.312 h
October	27.3°C24.2°C	24.2°C	20	2.9	11.712 h
November	26.1°C23.4°C	23.4°C	40	4.9	11.111 h
December	25.0°C22.3°C	22.3°C	47	5.1	10.911 h

Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.

Read the numbers correctly

Climate, not a promise.

These patterns help compare months. They cannot tell you the weather on a specific day of your trip.

Sources, method and limits

How these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Honolulu) is explained once on the Honolulu year overview and on the Sources, method and limits page.