Kailua weather in September

In September, Kailua sees average daytime highs of 81°F and overnight lows near 75°F, with 1.1 in of rain across 9.2 wet days and about 12.1 hours of daylight. It is the 1st-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 81°F through the month. The sky is clear or mostly clear about 62% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 24 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Kailua's 1st-clearest and 8th-windiest month. For the whole year in context, see Kailua's year-round climate.

Daytime high
81°
1st warmest
Overnight low
75°
12th coldest
Rainfall
1.1 in
9.2 wet days
Daylight
12 h 06 min
6:22 AM – 6:29 PM
Cloud cover
40%
1st clearest
Wind
13 mph
8th windiest
Solar energy
6.4 kWh/m²
Travel score
6.9
out of 10

Kailua is census designated place in Honolulu County, Hawaii, United States.

Density
1,411/km²
people per km²

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 81°F through the month.

A typical September day in Kailua reaches about 81°F in the afternoon and slips back to 75°F overnight — a 5°F spread between the day's warmth and the night's chill. On most days the high lands between 79°F and 83°F. Set against its neighbours, September runs on par with August and on par with October.

65°70°75°80°85°151015202530
Avg high (°F)Avg low (°F)
18175
28175
38175
48175
58175
68175
78175
88175
98175
108175
118175
128175
138175
148175
158175
168175
178175
188175
198175
208175
218175
228175
238175
248175
258175
268175
278175
288175
298175
308075

Kailua weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan75° / 69°1.78.210.87.6
Feb74° / 69°1.78.211.37.3
Mar74° / 69°2.310.711.87.0
Apr76° / 70°1.210.812.57.0
May77° / 72°1.38.9137.2
Jun79° / 73°1.210.413.36.9
Jul80° / 74°1.210.813.26.8
Aug80° / 75°1.29.512.76.9
Sep81° / 75°1.19.212.16.9
Oct80° / 74°1.51011.56.8
Nov78° / 73°2.311.3116.7
Dec76° / 71°2.310.610.77.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 62% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 20%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18218
28218
38218
48218
58218
68218
78218
88218
98218
108218
118218
128218
138218
148218
158119
168119
178119
188119
198119
208119
218119
228020
238020
248020
257921
267723
277723
287624
297624
307525

Chance of precipitation in September

Any precipitation

Kailua gets around 1.1 in of rain over 9.2 wet days in September, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 31% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
129
229
329
428
528
628
729
829
929
1030
1130
1231
1331
1431
1532
1632
1732
1832
1933
2033
2133
2232
2332
2432
2532
2631
2731
2831
2931
3031

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels muggy — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the muggy band about 62% of days. Sticky, muggy-or-worse air turns up on roughly 98% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)
116435
216435
316435
416435
516336
616336
726236
826137
926137
1026137
1126137
1226137
1326137
1426137
1526236
1626236
1726236
1826236
1926236
2026236
2126236
2226236
2326236
2426236
2526236
2626236
2726236
2826236
2926236
3026236

Wind in September

Winds average 13 mph in September.

Across September, daily wind ranges from about 12 mph on the calmest days to 13 mph at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (mph)Feels
113breezy
213breezy
313breezy
413breezy
513breezy
613breezy
713breezy
813breezy
913breezy
1013breezy
1113breezy
1213breezy
1313breezy
1413breezy
1513breezy
1613breezy
1713breezy
1813breezy
1913breezy
2012breezy
2112breezy
2212breezy
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 24 min at the start of September to 11 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 36 minutes over September. Sunrise moves from 6:18 AM to 6:25 AM, and sunset from 6:44 PM to 6:15 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:186:44
212.46:186:43
312.46:186:42
412.46:196:41
512.46:196:40
612.36:196:39
712.36:196:38
812.36:206:37
912.36:206:36
1012.26:206:35
1112.26:206:34
1212.26:216:33
1312.26:216:32
1412.26:216:31
1512.16:216:30
1612.16:226:29
1712.16:226:28
1812.16:226:27
1912.16:226:26
2012.06:236:25
2112.06:236:24
2212.06:236:23
2312.06:236:22
2412.06:246:21
2511.96:246:20
2611.96:246:19
2711.96:256:18
2811.96:256:17
2911.86:256:16
3011.86:256:15

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.4 kWh/m².

For context, solar energy here swings from a low near 4.19 kWh/m² to a high of 7.18 kWh/m² in June across the year — September's 6.4 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.7Intense
26.7Intense
36.7Intense
46.6Intense
56.6Intense
66.6Intense
76.6Intense
86.6Intense
96.5Intense
106.5Intense
116.5Intense
126.5Intense
136.5Intense
146.4Intense
156.4Intense
166.4Intense
176.4Intense
186.3Intense
196.3Intense
206.3Intense
216.3Intense
226.2Intense
236.2Intense
246.2Intense
256.2Intense
266.1Intense
276.1Intense
286.1Intense
296.0Intense
306.0Bright
Planning a trip in September

Hazard calendar for Kailua

In seasonPeak

In September, Kailua sits inside its pacific hurricane season. The full year is below, with each hazard's peak months called out.

Kailua sits in the eastern Pacific hurricane zone; the season peaks August–September.

Pacific hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Kailua?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.9
Sightseeing
7th-best month of the year
7.0
Beach & pool
1st-best month of the year

September is a reasonable time to visit Kailua for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Kailua in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Kailua sees daytime highs around 81°F and nights near 75°F. Pack light clothes and sun protection. Worth having: rain gear and a windbreaker. About 9 days see rain.

light clothessun protectionrain geara windbreaker

Sea temperature near Kailua in September

The nearest coast averages about 80°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in September at about 80°F and coldest in February near 75°F.

The water stays above 68°F all year — warm enough for a swim any month.

74°76°78°80°82°JanFebMarAprMayJunJulAugSepOctNovDecrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan76Warm
Feb75Refreshing
Mar75Refreshing
Apr76Warm
May77Warm
Jun78Warm
Jul79Warm
Aug80Warm
Sep80Warm
Oct80Warm
Nov79Warm
Dec77Warm

UV index in Kailua in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Kailua peaks around July 22 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 6 (high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highExtremeVery highHighJul 22UV 12Dec 18UV 6
UV index (midday)Level
Jan6High
Feb8Very high
Mar10Extreme
Apr11Extreme
May10Very high
Jun11Extreme
Jul12Extreme
Aug12Extreme
Sep12Extreme
Oct9Very high
Nov7High
Dec6High
Location & terrain

Where is Kailua?

Kailua sits at 21.4°N, 157.7°W, 33 ft above sea level, in United States. The nearest listed city is Kaneohe, 3.7 mi away.

Topography around Kailua

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Kailua.

Within 2 miles, the terrain around Kailua has only modest variations in elevation — a maximum elevation change of 545 ft around an average of 39 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,117 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 3,983 ft.

The land around Kailua is covered by water (33%) and artificial surfaces (26%) within 2 miles, water (56%) and trees (27%) within 10 miles, and water (86%) within 50 miles.

2 miles
545 ft
10 miles
3,117 ft
50 miles
3,983 ft
treesshrubsgrasslandartificial surfaceswaterwetland
September weather nearby: Kaneohe 3.7 mi · Nuuanu - Punchbowl 6.8 mi · Kalihi Valley 6.8 mi · Manoa 7.5 mi · Kuliouou - Kalani Iki 7.5 mi · Hawai‘i Kai 7.5 mi · East Honolulu 8.1 mi · Niu Valley 8.1 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Kailua (21.4024°, -157.7405°, elevation 33 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).