Kirkland weather in September

In September, Kirkland sees average daytime highs of 66°F and overnight lows near 53°F, with 2.8 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 69°F in the first days to 63°F by the end. The sky is clear or mostly clear about 42% 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 Kirkland's 3rd-clearest and 9th-windiest month. For the whole year in context, see Kirkland's year-round climate.

Daytime high
66°
3rd warmest
Overnight low
53°
10th coldest
Rainfall
2.8 in
8.7 wet days
Daylight
12 h 18 min
5:53 AM – 6:13 PM
Cloud cover
47%
3rd clearest
Wind
5 mph
9th windiest
Solar energy
3.99 kWh/m²
Travel score
6.5
out of 10

Kirkland is city in King County, Washington, United States.

Density
6,941/km²
people per km²
Founded
1888

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 69°F in the first days to 63°F by the end.

A typical September day in Kirkland reaches about 66°F in the afternoon and slips back to 53°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 60°F and 74°F. Set against its neighbours, September runs about 6°F cooler than August and about 9°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17055
26955
36954
46954
56954
66954
76954
86854
96854
106853
116853
126753
136753
146753
156753
166653
176653
186652
196652
206552
216552
226552
236551
246551
256451
266451
276451
286350
296350
306350

Kirkland 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
Jan46° / 39°7.118.32.18.70.9
Feb48° / 39°4.714.91.89.91.5
Mar51° / 41°5.517.80.811.62.1
Apr56° / 44°4.415.40.113.33.2
May62° / 48°3.112.5014.94.9
Jun66° / 52°2.810.7015.75.9
Jul71° / 56°1.36015.47.6
Aug72° / 56°1.55.2014.17.7
Sep66° / 53°2.88.7012.46.5
Oct58° / 47°5.614.6010.63.8
Nov50° / 42°7.818.10.69.11.7
Dec45° / 38°7.117.92.18.30.8

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 42% 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 42%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16139
26238
36337
46337
56337
66238
76238
86238
96139
106139
116040
126040
135941
145941
155842
165842
175743
185743
195743
205644
215644
225545
235545
245545
255545
265545
275545
285446
295446
305248

Chance of precipitation in September

Any precipitation

Kirkland gets around 2.8 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 29% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
125
225
326
426
526
627
727
827
928
1029
1129
1230
1330
1431
1531
1631
1731
1831
1931
2031
2131
2231
2331
2431
2531
2631
2731
2831
2931
3031

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 82% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
174260
273261
374251
475241
575241
676231
776231
877221
978211
1078211
1179201
1279201
1380191
1480191
1582180
1682180
1783170
1883170
1984160
2085150
2185150
2286140
2387130
2488120
2589110
2689110
2790100
289190
299190
309280

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 6:45 PM to 5:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.25:326:45
213.25:346:43
313.15:356:41
413.05:366:39
513.05:386:37
612.95:396:35
712.95:406:32
812.85:426:30
912.85:436:28
1012.75:456:26
1112.65:466:24
1212.65:476:22
1312.55:496:20
1412.55:506:18
1512.45:526:15
1612.35:536:13
1712.35:546:11
1812.25:566:09
1912.25:576:07
2012.15:596:05
2112.06:006:03
2212.06:016:00
2311.96:035:58
2411.96:045:56
2511.86:065:54
2611.76:075:52
2711.76:085:50
2811.66:105:48
2911.66:115:46
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 3.99 kWh/m².

For context, solar energy here swings from a low near 0.86 kWh/m² to a high of 6.07 kWh/m² in July across the year — September's 3.99 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.6Bright
34.6Bright
44.5Bright
54.5Bright
64.5Bright
74.4Bright
84.4Bright
94.3Bright
104.3Bright
114.2Bright
124.1Bright
134.1Bright
144.0Bright
154.0Moderate
163.9Moderate
173.9Moderate
183.8Moderate
193.8Moderate
203.7Moderate
213.6Moderate
223.6Moderate
233.5Moderate
243.5Moderate
253.5Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.2Moderate
303.2Moderate
Planning a trip in September

Hazard calendar for Kirkland

In seasonPeak

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

Kirkland'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 Kirkland?

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

6.5
Sightseeing
3rd-best month of the year
2.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Kirkland for sightseeing.

What to pack for Kirkland in September

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

In September, Kirkland sees daytime highs around 66°F and nights near 53°F. Worth packing: rain gear. About 9 days see rain.

rain gear

Sea temperature near Kirkland 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 44 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 Kirkland 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 Kirkland 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 Kirkland 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 Kirkland 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 Kirkland?

Kirkland sits at 47.7°N, 122.2°W, 154 ft above sea level, in United States. The nearest listed city is Inglewood-Finn Hill, 3.1 mi away.

Topography around Kirkland

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

Within 2 miles, the terrain around Kirkland has only modest variations in elevation — a maximum elevation change of 600 ft around an average of 138 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,188 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,799 ft.

The land around Kirkland is covered by water (40%), trees (38%) and artificial surfaces (20%) within 2 miles, trees (57%) and artificial surfaces (21%) within 10 miles, and trees (73%) within 50 miles.

2 miles
600 ft
10 miles
1,188 ft
50 miles
7,799 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Inglewood-Finn Hill 3.1 mi · Redmond 4.3 mi · Bellevue 5.0 mi · Kenmore 5.6 mi · Bothell 5.6 mi · Sammamish 6.8 mi · Cottage Lake 7.5 mi · Mercer Island 7.5 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 Kirkland (47.6815°, -122.2087°, elevation 154 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).