Oak Harbor weather in September

In September, Oak Harbor sees average daytime highs of 59°F and overnight lows near 55°F, with 2.3 in of rain across 8.7 wet days and about 12.4 hours of daylight. It is the 3rd-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 61°F in the first days to 58°F by the end. The sky is clear or mostly clear about 46% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Oak Harbor's 3rd-clearest and 12th-windiest month. For the whole year in context, see Oak Harbor's year-round climate.

Daytime high: 59°; 3rd warmest
Overnight low: 55°; 10th coldest
Rainfall: 2.3 in; 8.7 wet days
Daylight: 12 h 18 min; 5:54 AM – 6:15 PM
Cloud cover: 46%; 3rd clearest
Wind: 6 mph; 12th windiest
Solar energy: 4.09 kWh/m²
Travel score: 5.0; out of 10

Oak Harbor is city on Whidbey Island in Island County, Washington State, United States.

Density: 925/km²; people per km²
Founded: 1915

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

← August Oak Harbor year-round climate October →Best places to visit in September

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 61°F in the first days to 58°F by the end.

A typical September day in Oak Harbor reaches about 59°F in the afternoon and slips back to 55°F overnight — a 4°F spread between the day's warmth and the night's chill. On most days the high lands between 56°F and 63°F. Set against its neighbours, September runs about 3°F cooler than August and about 5°F warmer than October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°F)	61	61	61	61	61	61	61	60	60	60	60	60	60	60	60	60	59	59	59	59	59	59	58	58	58	58	58	58	58	57
Avg low (°F)	56	56	56	56	56	56	56	56	56	56	56	56	56	55	55	55	55	55	55	55	55	55	54	54	54	54	54	54	53	53

	Avg high (°F)	Avg low (°F)
1	61	56
2	61	56
3	61	56
4	61	56
5	61	56
6	61	56
7	61	56
8	60	56
9	60	56
10	60	56
11	60	56
12	60	56
13	60	56
14	60	55
15	60	55
16	60	55
17	59	55
18	59	55
19	59	55
20	59	55
21	59	55
22	59	55
23	58	54
24	58	54
25	58	54
26	58	54
27	58	54
28	58	54
29	58	53
30	57	53

Oak Harbor weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 9th-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	45° / 42°	6.2	18.6	1.4	8.6	0.9
Feb	46° / 42°	4.2	14.7	1.3	9.9	1.1
Mar	48° / 44°	4.8	17.9	0.3	11.6	1.5
Apr	51° / 46°	3.3	14	0	13.4	2.3
May	55° / 50°	2.6	10.5	0	14.9	3.5
Jun	58° / 53°	2.1	9.4	0	15.8	4.4
Jul	62° / 56°	1.2	5.8	0	15.5	6.0
Aug	62° / 57°	1.4	5.3	0	14.1	6.3
Sep	59° / 55°	2.3	8.7	0	12.4	5.0
Oct	54° / 50°	4.7	13.8	0	10.6	3.1
Nov	49° / 45°	7.2	18.5	0.3	9	1.6
Dec	45° / 42°	6.4	18.1	1.4	8.2	0.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 46% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 40%. Skies tend to cloud over as the month goes on.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	63	63	63	64	64	64	64	64	64	63	63	62	61	60	60	59	59	58	58	58	57	57	57	58	58	58	57	57	57	56
Cloudier (%)	37	37	37	36	36	36	36	36	36	37	37	38	39	40	40	41	41	42	42	42	43	43	43	42	42	42	43	43	43	44

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	63	37
4	64	36
5	64	36
6	64	36
7	64	36
8	64	36
9	64	36
10	63	37
11	63	37
12	62	38
13	61	39
14	60	40
15	60	40
16	59	41
17	59	41
18	58	42
19	58	42
20	58	42
21	57	43
22	57	43
23	57	43
24	58	42
25	58	42
26	58	42
27	57	43
28	57	43
29	57	43
30	56	44

Chance of precipitation in September

Any precipitation

Oak Harbor gets around 2.3 in of rain over 8.7 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 30% and peaks near 33% on the wettest days. The odds climb toward the end of the month.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	23	23	24	24	25	25	26	26	27	29	30	31	31	32	32	33	33	33	33	33	33	33	33	32	32	31	31	31	31	31

	Rain chance (%)
1	23
2	23
3	24
4	24
5	25
6	25
7	26
8	26
9	27
10	29
11	30
12	31
13	31
14	32
15	32
16	33
17	33
18	33
19	33
20	33
21	33
22	33
23	33
24	32
25	32
26	31
27	31
28	31
29	31
30	31

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 92% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dry (%)	86	87	87	87	88	88	89	89	89	89	90	90	90	90	91	91	91	92	92	93	93	94	95	95	96	97	97	98	98	99
Comfortable (%)	14	13	13	13	12	12	11	11	11	11	10	10	10	10	9	9	9	8	8	7	7	6	5	5	4	3	3	2	2	1

	Dry (%)	Comfortable (%)
1	86	14
2	87	13
3	87	13
4	87	13
5	88	12
6	88	12
7	89	11
8	89	11
9	89	11
10	89	11
11	90	10
12	90	10
13	90	10
14	90	10
15	91	9
16	91	9
17	91	9
18	92	8
19	92	8
20	93	7
21	93	7
22	94	6
23	95	5
24	95	5
25	96	4
26	97	3
27	97	3
28	98	2
29	98	2
30	99	1

Wind in September

Winds average 6 mph in September, the calmest month.

Across September, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (mph)	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	7	7	7	7
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (mph)	Feels
1	6	calm
2	6	calm
3	6	calm
4	6	calm
5	6	calm
6	6	calm
7	6	calm
8	6	calm
9	6	calm
10	6	calm
11	6	calm
12	6	calm
13	6	calm
14	6	calm
15	6	calm
16	6	calm
17	6	calm
18	6	calm
19	6	calm
20	6	calm
21	6	calm
22	6	calm
23	6	calm
24	6	calm
25	6	calm
26	6	calm
27	7	calm
28	7	calm
29	7	calm
30	7	calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 12 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 102 minutes over September. Sunrise moves from 5:33 AM to 6:15 AM, and sunset from 6:47 PM to 5:45 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	13.2	13.2	13.1	13.1	13.0	12.9	12.9	12.8	12.8	12.7	12.6	12.6	12.5	12.5	12.4	12.3	12.3	12.2	12.2	12.1	12.0	12.0	11.9	11.9	11.8	11.7	11.7	11.6	11.6	11.5
Sunrise (AM)	5:33	5:35	5:36	5:37	5:39	5:40	5:42	5:43	5:44	5:46	5:47	5:49	5:50	5:52	5:53	5:54	5:56	5:57	5:59	6:00	6:02	6:03	6:05	6:06	6:07	6:09	6:10	6:12	6:13	6:15
Sunset (PM)	6:47	6:45	6:43	6:41	6:39	6:37	6:35	6:33	6:30	6:28	6:26	6:24	6:22	6:20	6:17	6:15	6:13	6:11	6:09	6:07	6:04	6:02	6:00	5:58	5:56	5:54	5:51	5:49	5:47	5:45

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.2	5:33	6:47
2	13.2	5:35	6:45
3	13.1	5:36	6:43
4	13.1	5:37	6:41
5	13.0	5:39	6:39
6	12.9	5:40	6:37
7	12.9	5:42	6:35
8	12.8	5:43	6:33
9	12.8	5:44	6:30
10	12.7	5:46	6:28
11	12.6	5:47	6:26
12	12.6	5:49	6:24
13	12.5	5:50	6:22
14	12.5	5:52	6:20
15	12.4	5:53	6:17
16	12.3	5:54	6:15
17	12.3	5:56	6:13
18	12.2	5:57	6:11
19	12.2	5:59	6:09
20	12.1	6:00	6:07
21	12.0	6:02	6:04
22	12.0	6:03	6:02
23	11.9	6:05	6:00
24	11.9	6:06	5:58
25	11.8	6:07	5:56
26	11.7	6:09	5:54
27	11.7	6:10	5:51
28	11.6	6:12	5:49
29	11.6	6:13	5:47
30	11.5	6:15	5:45

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.09 kWh/m².

For context, solar energy here swings from a low near 0.88 kWh/m² to a high of 6.3 kWh/m² in July across the year — September's 4.09 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	4.8	4.7	4.7	4.7	4.6	4.6	4.5	4.5	4.4	4.4	4.3	4.2	4.2	4.1	4.1	4.0	4.0	3.9	3.9	3.8	3.8	3.7	3.6	3.6	3.5	3.5	3.5	3.4	3.3	3.3
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	4.8	Bright
2	4.7	Bright
3	4.7	Bright
4	4.7	Bright
5	4.6	Bright
6	4.6	Bright
7	4.5	Bright
8	4.5	Bright
9	4.4	Bright
10	4.4	Bright
11	4.3	Bright
12	4.2	Bright
13	4.2	Bright
14	4.1	Bright
15	4.1	Bright
16	4.0	Bright
17	4.0	Moderate
18	3.9	Moderate
19	3.9	Moderate
20	3.8	Moderate
21	3.8	Moderate
22	3.7	Moderate
23	3.6	Moderate
24	3.6	Moderate
25	3.5	Moderate
26	3.5	Moderate
27	3.5	Moderate
28	3.4	Moderate
29	3.3	Moderate
30	3.3	Moderate

Planning a trip in September

Hazard calendar for Oak Harbor

In seasonPeak

None of Oak Harbor's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Oak Harbor's rainy season runs October–April, when most of the year's rain falls.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is September a good time to visit Oak Harbor?

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

5.0

Sightseeing

3rd-best month of the year

0.3

Beach & pool

3rd-best month of the year

September is a reasonable time to visit Oak Harbor for sightseeing.

What to pack for Oak Harbor in September

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

In September, Oak Harbor sees daytime highs around 59°F and nights near 55°F. Worth packing: a warm layer and rain gear. About 9 days see rain.

a warm layerrain gear

Sea temperature near Oak Harbor in September

The nearest coast averages about 53°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 12 mi away) is warmest in August at about 54°F and coldest in February near 46°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sea temperature (°F)	46	46	47	48	50	52	53	54	53	50	49	47
Comfort	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing

	Sea temperature (°F)	Comfort
Jan	46	Bracing
Feb	46	Bracing
Mar	47	Bracing
Apr	48	Bracing
May	50	Bracing
Jun	52	Bracing
Jul	53	Bracing
Aug	54	Bracing
Sep	53	Bracing
Oct	50	Bracing
Nov	49	Bracing
Dec	47	Bracing

UV index in Oak Harbor in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Oak Harbor peaks around July 17 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 18 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	1	1	4	5	7	6	8	6	4	3	1	1
Level	Low	Low	Moderate	Moderate	High	High	Very high	High	Moderate	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	1	Low
Mar	4	Moderate
Apr	5	Moderate
May	7	High
Jun	6	High
Jul	8	Very high
Aug	6	High
Sep	4	Moderate
Oct	3	Moderate
Nov	1	Low
Dec	1	Low

Location & terrain

Where is Oak Harbor?

Oak Harbor sits at 48.3°N, 122.6°W, 95 ft above sea level, in United States. The nearest listed city is Anacortes, 15 mi away.

Topography around Oak Harbor

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

Within 2 miles, the terrain around Oak Harbor has only modest variations in elevation — a maximum elevation change of 354 ft around an average of 89 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 771 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,780 ft.

The land around Oak Harbor is covered by water (29%), trees (28%) and grassland (24%) within 2 miles, water (61%) and trees (23%) within 10 miles, and trees (53%) and water (34%) within 50 miles.

2 miles

354 ft

water 29%

10 miles

771 ft

water 61%

50 miles

9,780 ft

trees 53%

treesgrasslandcroplandartificial surfacesbare terrainwaterwetland

← August Oak Harbor year-round climate October →Best places to visit in September

September weather nearby: Anacortes 15 mi · Mount Vernon 17 mi · Arlington 25 mi · Marysville 27 mi · Mukilteo 29 mi · Everett 30 mi · Oak Bay 32 mi · West Lake Stevens 32 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

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 Oak Harbor (48.2932°, -122.6432°, elevation 95 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. 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).

	Avg high (°F)	Avg low (°F)
1	61	56
2	61	56
3	61	56
4	61	56
5	61	56
6	61	56
7	61	56
8	60	56
9	60	56
10	60	56
11	60	56
12	60	56
13	60	56
14	60	55
15	60	55
16	60	55
17	59	55
18	59	55
19	59	55
20	59	55
21	59	55
22	59	55
23	58	54
24	58	54
25	58	54
26	58	54
27	58	54
28	58	54
29	58	53
30	57	53

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	63	37
4	64	36
5	64	36
6	64	36
7	64	36
8	64	36
9	64	36
10	63	37
11	63	37
12	62	38
13	61	39
14	60	40
15	60	40
16	59	41
17	59	41
18	58	42
19	58	42
20	58	42
21	57	43
22	57	43
23	57	43
24	58	42
25	58	42
26	58	42
27	57	43
28	57	43
29	57	43
30	56	44

	Rain chance (%)
1	23
2	23
3	24
4	24
5	25
6	25
7	26
8	26
9	27
10	29
11	30
12	31
13	31
14	32
15	32
16	33
17	33
18	33
19	33
20	33
21	33
22	33
23	33
24	32
25	32
26	31
27	31
28	31
29	31
30	31

	Dry (%)	Comfortable (%)
1	86	14
2	87	13
3	87	13
4	87	13
5	88	12
6	88	12
7	89	11
8	89	11
9	89	11
10	89	11
11	90	10
12	90	10
13	90	10
14	90	10
15	91	9
16	91	9
17	91	9
18	92	8
19	92	8
20	93	7
21	93	7
22	94	6
23	95	5
24	95	5
25	96	4
26	97	3
27	97	3
28	98	2
29	98	2
30	99	1

	Avg high (°F)	Avg low (°F)
1	61	56
2	61	56
3	61	56
4	61	56
5	61	56
6	61	56
7	61	56
8	60	56
9	60	56
10	60	56
11	60	56
12	60	56
13	60	56
14	60	55
15	60	55
16	60	55
17	59	55
18	59	55
19	59	55
20	59	55
21	59	55
22	59	55
23	58	54
24	58	54
25	58	54
26	58	54
27	58	54
28	58	54
29	58	53
30	57	53

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	63	37
4	64	36
5	64	36
6	64	36
7	64	36
8	64	36
9	64	36
10	63	37
11	63	37
12	62	38
13	61	39
14	60	40
15	60	40
16	59	41
17	59	41
18	58	42
19	58	42
20	58	42
21	57	43
22	57	43
23	57	43
24	58	42
25	58	42
26	58	42
27	57	43
28	57	43
29	57	43
30	56	44

	Rain chance (%)
1	23
2	23
3	24
4	24
5	25
6	25
7	26
8	26
9	27
10	29
11	30
12	31
13	31
14	32
15	32
16	33
17	33
18	33
19	33
20	33
21	33
22	33
23	33
24	32
25	32
26	31
27	31
28	31
29	31
30	31

	Dry (%)	Comfortable (%)
1	86	14
2	87	13
3	87	13
4	87	13
5	88	12
6	88	12
7	89	11
8	89	11
9	89	11
10	89	11
11	90	10
12	90	10
13	90	10
14	90	10
15	91	9
16	91	9
17	91	9
18	92	8
19	92	8
20	93	7
21	93	7
22	94	6
23	95	5
24	95	5
25	96	4
26	97	3
27	97	3
28	98	2
29	98	2
30	99	1

	Avg high (°F)	Avg low (°F)
1	61	56
2	61	56
3	61	56
4	61	56
5	61	56
6	61	56
7	61	56
8	60	56
9	60	56
10	60	56
11	60	56
12	60	56
13	60	56
14	60	55
15	60	55
16	60	55
17	59	55
18	59	55
19	59	55
20	59	55
21	59	55
22	59	55
23	58	54
24	58	54
25	58	54
26	58	54
27	58	54
28	58	54
29	58	53
30	57	53

	Clearer (%)	Cloudier (%)
1	63	37
2	63	37
3	63	37
4	64	36
5	64	36
6	64	36
7	64	36
8	64	36
9	64	36
10	63	37
11	63	37
12	62	38
13	61	39
14	60	40
15	60	40
16	59	41
17	59	41
18	58	42
19	58	42
20	58	42
21	57	43
22	57	43
23	57	43
24	58	42
25	58	42
26	58	42
27	57	43
28	57	43
29	57	43
30	56	44

	Rain chance (%)
1	23
2	23
3	24
4	24
5	25
6	25
7	26
8	26
9	27
10	29
11	30
12	31
13	31
14	32
15	32
16	33
17	33
18	33
19	33
20	33
21	33
22	33
23	33
24	32
25	32
26	31
27	31
28	31
29	31
30	31

	Dry (%)	Comfortable (%)
1	86	14
2	87	13
3	87	13
4	87	13
5	88	12
6	88	12
7	89	11
8	89	11
9	89	11
10	89	11
11	90	10
12	90	10
13	90	10
14	90	10
15	91	9
16	91	9
17	91	9
18	92	8
19	92	8
20	93	7
21	93	7
22	94	6
23	95	5
24	95	5
25	96	4
26	97	3
27	97	3
28	98	2
29	98	2
30	99	1