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Mercer Island, WA weather and climate

King County, WA · population 25,282 · about 46 ft elevation

Everything below is a 30 year average for 1991-2020, computed from daily climate history at Mercer Island's own coordinates.

The year at a glance

Sunny days
147
clear or partly cloudy, per year
Precipitation
52 in
per year
Wet days
155
rain or snow per year
Snowfall
6 in
per year
Hot days
3
above 90 °F
Freezing nights
29
at or below 32 °F
Humidity
79%
average relative
Average temperature
54 °F
year round

Monthly temperatures

Average daily high and low for each month, in °F.

Daily highDaily low
406080JanMarMayJulSepNovDaily high, Jan: 48 °FDaily high, Feb: 51 °FDaily high, Mar: 55 °FDaily high, Apr: 60 °FDaily high, May: 66 °FDaily high, Jun: 71 °FDaily high, Jul: 77 °FDaily high, Aug: 77 °FDaily high, Sep: 72 °FDaily high, Oct: 61 °FDaily high, Nov: 53 °FDaily high, Dec: 47 °FDaily low, Jan: 37 °FDaily low, Feb: 37 °FDaily low, Mar: 39 °FDaily low, Apr: 43 °FDaily low, May: 49 °FDaily low, Jun: 54 °FDaily low, Jul: 57 °FDaily low, Aug: 58 °FDaily low, Sep: 54 °FDaily low, Oct: 46 °FDaily low, Nov: 40 °FDaily low, Dec: 37 °F
View monthly temperatures as a table
Monthly temperatures (°F)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Daily high485155606671777772615347
Daily low373739434954575854464037

Monthly precipitation

Total rain plus melted snow for each month, in inches.

0.02.55.07.5JanMarMayJulSepNovMercer Island, Jan: 6.9 inMercer Island, Feb: 4.8 inMercer Island, Mar: 5.5 inMercer Island, Apr: 4.5 inMercer Island, May: 3.0 inMercer Island, Jun: 2.3 inMercer Island, Jul: 1.0 inMercer Island, Aug: 1.3 inMercer Island, Sep: 2.6 inMercer Island, Oct: 5.3 inMercer Island, Nov: 7.6 inMercer Island, Dec: 7.0 in
View monthly precipitation as a table
Monthly precipitation (inches)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Mercer Island6.94.85.54.53.02.31.01.32.65.37.67.0

Monthly sunny days

Days each month with clear or partly cloudy skies.

01020JanMarMayJulSepNovMercer Island, Jan: 7 daysMercer Island, Feb: 10 daysMercer Island, Mar: 9 daysMercer Island, Apr: 10 daysMercer Island, May: 12 daysMercer Island, Jun: 13 daysMercer Island, Jul: 20 daysMercer Island, Aug: 21 daysMercer Island, Sep: 18 daysMercer Island, Oct: 12 daysMercer Island, Nov: 8 daysMercer Island, Dec: 7 days
View monthly sunny days as a table
Monthly sunny days (days)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Mercer Island71091012132021181287

Compare Mercer Island with another city

Nearby cities and popular picks. Any two cities can be compared from the home page.

See weather for every covered Washington city

About this data

Figures are 30 year averages for 1991-2020. Wet days count days with measurable precipitation, calibrated against the wet day counts in NOAA's published climate normals. Sunny days count clear plus partly cloudy days, defined as average cloud cover of 63 percent or less and calibrated against NOAA's published sky cover tables. Snowfall figures are model estimates anchored to NOAA station measurements near each city.

Weather data by Open-Meteo.com (CC BY 4.0). Contains modified Copernicus Climate Change Service information (ERA5, ERA5-Land).