West Lake Sammamish in Fall
In fall (September, October and November), West Lake Sammamish sees average daytime highs around 59°F and overnight lows near 44°F, with 19.0 in of precipitation over about 43 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 71°F in early September to 46°F by late November. The sky is clear or mostly clear about 27% of the time across fall, and the air most often feels dry.
Fall is West Lake Sammamish's 2nd-best season to visit on our travel score. For the whole year in context, see West Lake Sammamish's year-round climate.
- Avg daytime high
- 59°F
- 2nd-warmest season
- Avg overnight low
- 44°F
- Precipitation
- 19.0 in
- 43 wet days
- Avg wind
- 5 mph
- Travel score
- 4.0
- 2nd-best season
- Months
- Sep · Oct · Nov
Temperature in West Lake Sammamish in Fall
Over the season highs ease from about 71°F in early September to 46°F by late November.
A typical fall day in West Lake Sammamish reaches about 59°F and drops to 44°F overnight. The warmest of the three months is September, the coolest November.
How fall really feels in West Lake Sammamish
Once humidity and wind are folded in, fall brings about 0 days that feel above 90°F and 9 that feel at or below 32°F.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
West Lake Sammamish weather by month
How the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 45° / 35° | 8.3 | 18.7 | 3.6 | 8.7 | 0.8 |
| Feb | 48° / 36° | 5.8 | 15.5 | 2.6 | 9.9 | 1.5 |
| Mar | 52° / 37° | 6.5 | 18.7 | 1.8 | 11.6 | 2.2 |
| Apr | 57° / 41° | 5.4 | 16.5 | 0.2 | 13.3 | 3.4 |
| May | 63° / 46° | 3.8 | 12.8 | 0 | 14.9 | 5.1 |
| Jun | 67° / 50° | 3.2 | 11.4 | 0 | 15.7 | 5.9 |
| Jul | 74° / 54° | 1.3 | 6.5 | 0 | 15.4 | 7.7 |
| Aug | 74° / 54° | 1.6 | 5.7 | 0 | 14.1 | 7.9 |
| Sep | 68° / 49° | 3.4 | 9 | 0 | 12.4 | 6.6 |
| Oct | 58° / 43° | 6.6 | 15.1 | 0 | 10.6 | 3.9 |
| Nov | 49° / 38° | 9.0 | 18.7 | 1 | 9.1 | 1.6 |
| Dec | 44° / 35° | 8.1 | 18.4 | 3.4 | 8.3 | 0.6 |
Cloud cover in Fall
The sky is clear or mostly clear about 27% of the time across fall.
Chance of precipitation in Fall
West Lake Sammamish gets around 19.0 in of rain and snow over 43 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 5 mph across fall.
Sunrise & sunset in Fall
Daylight runs from about 13 h 12 min in early September to 8 h 30 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 2.5 kWh/m².
Hazard calendar for West Lake Sammamish
In fall, West Lake Sammamish overlaps its rainy season season. The full year is below, with each hazard's peak months called out.
West Lake Sammamish's rainy season runs October–April, when most of the year's rain falls.
Is fall a good time to visit West Lake Sammamish?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit West Lake Sammamish for sightseeing.
What to pack for West Lake Sammamish in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, West Lake Sammamish sees daytime highs around 59°F and nights near 44°F. Pack a warm layer and rain gear. About 43 days see rain.
UV index in West Lake Sammamish in Fall
Clear-sky midday UV across fall averages around 3. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in West Lake 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.
| 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 |
Air quality in West Lake Sammamish in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall falls, not just the annual average.
Air quality in West Lake Sammamish is worst in September — around 22 µg/m³ PM2.5 (moderate), about 3.4× the cleanest month (December, 7 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 8 | 9 | 12 | 12 | 11 | 10 | 10 | 18 | 22 | 12 | 8 | 7 |
| Level | Good | Good | Moderate | Good | Good | Good | Good | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 8 | Good |
| Feb | 9 | Good |
| Mar | 12 | Moderate |
| Apr | 12 | Good |
| May | 11 | Good |
| Jun | 10 | Good |
| Jul | 10 | Good |
| Aug | 18 | Moderate |
| Sep | 22 | Moderate |
| Oct | 12 | Good |
| Nov | 8 | Good |
| Dec | 7 | Good |
Where is West Lake Sammamish?
West Lake Sammamish sits at 47.6°N, 122.1°W, 30 ft above sea level, in United States. The nearest listed city is City of Sammamish, 3.7 mi away.
Topography around West Lake Sammamish
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of West Lake Sammamish.
Within 2 miles, the terrain around West Lake Sammamish has significant variations in elevation — a maximum elevation change of 1,076 ft around an average of 272 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,005 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,695 ft.
The land around West Lake Sammamish is covered by trees (52%) and water (32%) within 2 miles, trees (66%) within 10 miles, and trees (76%) within 50 miles.
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 West Lake Sammamish (47.5776°, -122.1012°, elevation 30 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.