Mukilteo weather in September

In September, Mukilteo sees average daytime highs of 65°F and overnight lows near 52°F, with 3.3 in of rain across 9.4 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 67°F in the first days to 62°F by the end. The sky is clear or mostly clear about 43% 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 Mukilteo's 3rd-clearest and 9th-windiest month. For the whole year in context, see Mukilteo's year-round climate.

Daytime high
65°
3rd warmest
Overnight low
52°
10th coldest
Rainfall
3.3 in
9.4 wet days
Daylight
12 h 18 min
5:53 AM – 6:14 PM
Cloud cover
48%
3rd clearest
Wind
5 mph
9th windiest
Solar energy
3.96 kWh/m²
Travel score
6.1
out of 10

Mukilteo is waterfront city in Snohomish County, Washington, United States.

Density
862/km²
people per km²
Founded
1858

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 67°F in the first days to 62°F by the end.

A typical September day in Mukilteo reaches about 65°F in the afternoon and slips back to 52°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 58°F and 72°F. Set against its neighbours, September runs about 5°F cooler than August and about 8°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
16854
26754
36754
46754
56753
66753
76753
86653
96653
106653
116653
126653
136553
146552
156552
166552
176552
186452
196452
206451
216451
226351
236351
246351
256351
266250
276250
286250
296250
306149

How September really feels in Mukilteo

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Mukilteo 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.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan45° / 38°9.119.358.60.7
Feb47° / 38°5.815.44.29.91.2
Mar50° / 40°7.019.13.111.61.8
Apr54° / 43°5.2160.813.42.8
May60° / 47°3.512.30.114.94.5
Jun64° / 51°3.110.6015.75.6
Jul69° / 55°1.56.1015.47.3
Aug70° / 55°1.76.1014.17.4
Sep65° / 52°3.39.4012.46.1
Oct56° / 46°7.115010.63.5
Nov48° / 41°10.019.31.991.4
Dec44° / 38°9.119.15.38.20.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 41%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16238
26337
36337
46337
56337
66436
76337
86337
96238
106139
116040
126040
135941
145941
155842
165842
175743
185743
195644
205644
215743
225743
235644
245644
255644
265644
275644
285545
295545
305347

Chance of precipitation in September

Any precipitation

Mukilteo gets around 3.3 in of rain over 9.4 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 32% and peaks near 34% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
128
228
328
429
529
629
729
830
931
1031
1132
1233
1333
1434
1534
1634
1734
1834
1934
2034
2134
2234
2333
2433
2533
2632
2732
2832
2932
3033

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 87% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)
17822
27921
37921
48020
58119
68119
78218
88317
98416
108416
118515
128515
138614
148614
158713
168713
178812
188812
198911
208911
219010
229010
23919
24928
25928
26937
27946
28946
29955
30955

Wind in September

Winds average 5 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

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 5:32 AM to 6:13 AM, and sunset from 6:46 PM to 5:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.25:326:46
213.25:346:44
313.15:356:42
413.15:366:39
513.05:386:37
612.95:396:35
712.95:416:33
812.85:426:31
912.85:436:29
1012.75:456:27
1112.65:466:25
1212.65:486:22
1312.55:496:20
1412.55:506:18
1512.45:526:16
1612.35:536:14
1712.35:556:12
1812.25:566:10
1912.25:586:07
2012.15:596:05
2112.06:006:03
2212.06:026:01
2311.96:035:59
2411.96:055:57
2511.86:065:54
2611.76:075:52
2711.76:095:50
2811.66:105:48
2911.66:125:46
3011.56:135:44

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.96 kWh/m².

For context, solar energy here swings from a low near 0.84 kWh/m² to a high of 6.04 kWh/m² in July across the year — September's 3.96 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.6Bright
44.5Bright
54.5Bright
64.4Bright
74.4Bright
84.3Bright
94.3Bright
104.2Bright
114.2Bright
124.1Bright
134.1Bright
144.0Bright
153.9Moderate
163.9Moderate
173.8Moderate
183.8Moderate
193.7Moderate
203.7Moderate
213.6Moderate
223.6Moderate
233.5Moderate
243.5Moderate
253.4Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.2Moderate
303.1Moderate
Planning a trip in September

Hazard calendar for Mukilteo

In seasonPeak

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

Mukilteo'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 Mukilteo?

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

6.1
Sightseeing
3rd-best month of the year
2.2
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Mukilteo for sightseeing.

What to pack for Mukilteo in September

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

In September, Mukilteo sees daytime highs around 65°F and nights near 52°F. Worth packing: rain gear. About 9 days see rain.

rain gear

Sea temperature near Mukilteo 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 29 mi away) is warmest in August at about 53°F and coldest in February near 46°F.

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

45°50°55°JanFebMarAprMayJunJulAugSepOctNovDecbracing
Sea temperature (°F)Comfort
Jan46Bracing
Feb46Bracing
Mar47Bracing
Apr48Bracing
May50Bracing
Jun52Bracing
Jul53Bracing
Aug53Bracing
Sep53Bracing
Oct50Bracing
Nov49Bracing
Dec47Bracing

UV index in Mukilteo 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 Mukilteo 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.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 17UV 8Dec 18UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar4Moderate
Apr5Moderate
May7High
Jun6High
Jul8Very high
Aug6High
Sep4Moderate
Oct3Moderate
Nov1Low
Dec1Low

Air quality in Mukilteo in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Mukilteo is worst in August — around 20 µg/m³ PM2.5 (moderate), about 3.1× the cleanest month (December, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodGoodModerateGoodModerateGoodAug 2119 µg/m³Dec 157 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb10Good
Mar12Moderate
Apr12Good
May13Moderate
Jun11Good
Jul10Good
Aug20Moderate
Sep18Moderate
Oct11Good
Nov7Good
Dec6Good
Location & terrain

Where is Mukilteo?

Mukilteo sits at 47.9°N, 122.3°W, 105 ft above sea level, in United States. The nearest listed city is Everett, 5.6 mi away.

Topography around Mukilteo

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

Within 2 miles, the terrain around Mukilteo has only modest variations in elevation — a maximum elevation change of 630 ft around an average of 157 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 682 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,589 ft.

The land around Mukilteo is covered by water (60%) and trees (24%) within 2 miles, water (41%) and trees (37%) within 10 miles, and trees (67%) and water (21%) within 50 miles.

2 miles
630 ft
10 miles
682 ft
50 miles
7,589 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Everett 5.6 mi · Picnic Point-North Lynnwood 5.6 mi · Eastmont 6.8 mi · Martha Lake 6.8 mi · Mill Creek 7.5 mi · Lynnwood 8.7 mi · Silver Firs 8.7 mi · Mill Creek East 9.3 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 Mukilteo (47.9445°, -122.3046°, elevation 105 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. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).