Sammamish weather in December

In December, Sammamish sees average daytime highs of 44°F and overnight lows near 35°F, with 8.7 in of precipitation across 18.7 wet days and about 8.3 hours of daylight. It is the 12th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 44°F through the month. The sky is clear or mostly clear about 13% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 30 min at the start of December to 8 h 18 min by month's end. Set against the rest of the year, December is Sammamish's 12th-clearest and 1st-windiest month. For the whole year in context, see Sammamish's year-round climate.

Daytime high
44°
12th warmest
Overnight low
35°
1st coldest
Precipitation
8.7 in
18.7 wet days
Daylight
8 h 12 min
7:57 AM – 4:12 PM
Cloud cover
77%
12th clearest
Wind
6 mph
1st windiest
Solar energy
0.86 kWh/m²
Travel score
0.6
out of 10

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

Density
1,092/km²
people per km²
Founded
1999

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 44°F through the month.

A typical December day in Sammamish reaches about 44°F in the afternoon and slips back to 35°F overnight — a 9°F spread between the day's warmth and the night's chill. On most days the high lands between 38°F and 50°F. Set against its neighbours, December runs about 5°F cooler than November and on par with January.

20°30°40°50°60°151015202531
Avg high (°F)Avg low (°F)
14536
24536
34535
44535
54535
64535
74535
84435
94435
104435
114435
124435
134435
144435
154435
164435
174435
184435
194435
204435
214435
224435
234435
244435
254435
264435
274435
284435
294435
304435
314435

How December really feels in Sammamish

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 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
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Sammamish weather by month

How December compares with the rest of the year at a glance. December is the 12th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan45° / 36°9.01948.70.8
Feb48° / 36°6.115.52.99.91.5
Mar52° / 38°7.119.12.311.62.2
Apr57° / 41°5.916.70.313.33.4
May63° / 46°4.113.2014.95.1
Jun67° / 51°3.511.4015.75.9
Jul73° / 54°1.66.3015.47.6
Aug74° / 54°1.85.7014.17.8
Sep68° / 49°3.79.2012.46.5
Oct58° / 43°7.415.3010.63.8
Nov49° / 38°9.919.10.99.11.6
Dec44° / 35°8.718.73.98.30.6

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 13% of the time in December, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 9% of December, with mostly cloudy or overcast conditions the remaining 78%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12872
22773
32773
42773
52773
62674
72674
82476
92476
102377
112278
122080
132080
142080
152080
161981
171981
181981
191981
202080
212080
222080
232179
242179
252278
262179
272278
282278
292278
302377
312278

Chance of precipitation in December

Any precipitationSnow

Sammamish gets around 8.7 in of rain and snow over 18.7 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 62% and peaks near 65% on the wettest days, and about 4 days bring snow.

0%20%40%60%80%151015202531
Rain chance (%)Snow chance (%)
1618
2619
3609
4609
5609
6609
7609
8619
9619
106210
116210
126310
136411
146411
156512
166512
176513
186414
196414
206315
216315
226216
236216
246116
256116
266116
276016
286116
296116
306116
316116

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 6 mph in December, the windiest month of the year.

Across December, 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.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 30 min at the start of December to 8 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:43 AM to 8:03 AM, and sunset from 4:13 PM to 4:20 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.57:434:13
28.57:444:13
38.57:454:13
48.47:464:12
58.47:474:12
68.47:484:12
78.47:494:11
88.37:504:11
98.37:514:11
108.37:524:11
118.37:534:11
128.37:544:11
138.37:554:11
148.37:564:11
158.27:574:11
168.27:574:12
178.27:584:12
188.27:594:12
198.27:594:12
208.28:004:13
218.28:004:13
228.28:014:14
238.28:014:14
248.28:024:15
258.28:024:15
268.28:024:16
278.28:034:17
288.28:034:17
298.28:034:18
308.38:034:19
318.38:034:20

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 0.86 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 0.86 kWh/m² to a high of 6.13 kWh/m² in July across the year — December's 0.86 kWh/m² sits near the bottom.

00.511.52151015202531
Solar energy (kWh/m²)Level
10.9Dim
20.9Dim
30.9Dim
40.9Dim
50.9Dim
60.9Dim
70.9Dim
80.9Dim
90.8Dim
100.8Dim
110.8Dim
120.8Dim
130.8Dim
140.8Dim
150.8Dim
160.8Dim
170.8Dim
180.8Dim
190.8Dim
200.8Dim
210.8Dim
220.8Dim
230.8Dim
240.8Dim
250.8Dim
260.8Dim
270.9Dim
280.9Dim
290.9Dim
300.9Dim
310.9Dim
Planning a trip in December

Hazard calendar for Sammamish

In seasonPeak

In December, Sammamish sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Sammamish'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 December a good time to visit Sammamish?

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

0.6
Sightseeing
12th-best month of the year
0.0
Beach & pool
8th-best month of the year

December is a weaker month for outdoor sightseeing in Sammamish.

What to pack for Sammamish in December

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

In December, Sammamish sees daytime highs around 44°F and nights near 35°F. Pack a warm layer and rain gear. Worth having: a heavy coat. About 19 days see rain.

a warm layerrain geara heavy coat

UV index in Sammamish in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Sammamish 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 17 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 17UV 1
UV index (midday)Level
Jan1Low
Feb1Low
Mar4Moderate
Apr5Moderate
May7High
Jun6High
Jul8Very high
Aug6High
Sep4Moderate
Oct3Moderate
Nov1Low
Dec1Low

Air quality in Sammamish in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Sammamish 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 Sammamish?

Sammamish sits at 47.6°N, 122.1°W, 59 ft above sea level, in United States. The nearest listed city is Redmond, 3.1 mi away.

Topography around Sammamish

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

Within 2 miles, the terrain around Sammamish has only modest variations in elevation — a maximum elevation change of 597 ft around an average of 217 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,503 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,799 ft.

The land around Sammamish is covered by trees (61%) and water (20%) within 2 miles, trees (69%) within 10 miles, and trees (75%) within 50 miles.

2 miles
597 ft
10 miles
2,503 ft
50 miles
7,799 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Redmond 3.1 mi · City of Sammamish 3.1 mi · Union Hill-Novelty Hill 3.7 mi · West Lake Sammamish 4.3 mi · Bellevue 6.2 mi · Kirkland 6.8 mi · Cottage Lake 6.8 mi · Issaquah 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 Sammamish (47.6418°, -122.0804°, elevation 59 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. 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).