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Climate & Weather Averages in San Juan Island, Washington, USA

Currently: 45 °F. Mostly cloudy. (Weather station: Whidbey Island, USA). See more current weather

Annual Weather Averages in Whidbey Island

Whidbey Island is 24 miles from San Juan Island, so the actual climate in San Juan Island can vary a bit.

Based on weather reports collected during 1992–2021.

All Year Climate & Weather Averages in San Juan Island

High Temp: 69 °F

Low Temp: 36 °F

Mean Temp: 51 °F

Precipitation: 1.78"

Humidity: 79%

Dew Point: 44 °F

Wind: 15 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

January Climate & Weather Averages in San Juan Island

High Temp: 48 °F

Low Temp: 37 °F

Mean Temp: 42 °F

Precipitation: 2.53"

Humidity: 80%

Dew Point: 37 °F

Wind: 18 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

February Climate & Weather Averages in San Juan Island

High Temp: 49 °F

Low Temp: 36 °F

Mean Temp: 42 °F

Precipitation: 1.89"

Humidity: 78%

Dew Point: 36 °F

Wind: 16 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

March Climate & Weather Averages in San Juan Island

High Temp: 53 °F

Low Temp: 39 °F

Mean Temp: 46 °F

Precipitation: 1.77"

Humidity: 76%

Dew Point: 38 °F

Wind: 18 mph

Pressure: 30.04 "Hg

Visibility: 8 mi

April Climate & Weather Averages in San Juan Island

High Temp: 57 °F

Low Temp: 42 °F

Mean Temp: 49 °F

Precipitation: 1.68"

Humidity: 75%

Dew Point: 41 °F

Wind: 16 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

May Climate & Weather Averages in San Juan Island

High Temp: 61 °F

Low Temp: 47 °F

Mean Temp: 54 °F

Precipitation: 1.73"

Humidity: 78%

Dew Point: 46 °F

Wind: 13 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

June Climate & Weather Averages in San Juan Island

High Temp: 65 °F

Low Temp: 50 °F

Mean Temp: 57 °F

Precipitation: 1.16"

Humidity: 78%

Dew Point: 49 °F

Wind: 13 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

July Climate & Weather Averages in San Juan Island

High Temp: 68 °F

Low Temp: 53 °F

Mean Temp: 60 °F

Precipitation: 0.70"

Humidity: 78%

Dew Point: 52 °F

Wind: 12 mph

Pressure: 30.07 "Hg

Visibility: 8 mi

August Climate & Weather Averages in San Juan Island

High Temp: 69 °F

Low Temp: 53 °F

Mean Temp: 61 °F

Precipitation: 0.82"

Humidity: 80%

Dew Point: 53 °F

Wind: 10 mph

Pressure: 30.04 "Hg

Visibility: 8 mi

September Climate & Weather Averages in San Juan Island

High Temp: 65 °F

Low Temp: 49 °F

Mean Temp: 57 °F

Precipitation: 1.22"

Humidity: 82%

Dew Point: 51 °F

Wind: 10 mph

Pressure: 30.04 "Hg

Visibility: 8 mi

October Climate & Weather Averages in San Juan Island

High Temp: 58 °F

Low Temp: 44 °F

Mean Temp: 51 °F

Precipitation: 2.18"

Humidity: 82%

Dew Point: 46 °F

Wind: 14 mph

Pressure: 30.06 "Hg

Visibility: 8 mi

November Climate & Weather Averages in San Juan Island

High Temp: 51 °F

Low Temp: 40 °F

Mean Temp: 46 °F

Precipitation: 3.06"

Humidity: 80%

Dew Point: 40 °F

Wind: 18 mph

Pressure: 30.04 "Hg

Visibility: 8 mi

December Climate & Weather Averages in San Juan Island

High Temp: 46 °F

Low Temp: 36 °F

Mean Temp: 41 °F

Precipitation: 2.60"

Humidity: 80%

Dew Point: 36 °F

Wind: 19 mph

Pressure: 30.05 "Hg

Visibility: 8 mi

Quick Climate Info

Hottest MonthAugust (61 °F avg)
Coldest MonthDecember (41 °F avg)
Wettest MonthNovember (3.06" avg)
Windiest MonthDecember (19 mph avg)
Annual precip.21.35" (per year)

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