San Juan County weather, town by town
2 places in San Juan County, Washington, each with its own live forecast and radar, and where a station sits close enough, measured weather records.
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Measured at the NOAA stations serving these towns, daily records 1998 to 2025. Station extremes, not official state records.
San Juan County Weather Facts
San Juan County has 2 places on myweatherrock (1 towns, 1 census-designated places), each with its own live forecast, hourly timeline, ten day outlook and radar. The hottest day in the station records is 101°F at Friday Harbor Ap on June 28, 2021. The coldest night is 8°F at Friday Harbor Ap on December 20, 2008. The wettest day brought 2.5 inches of rain at Friday Harbor Ap on December 21, 2020. The biggest single-day snow measured 25.59 inches at Saanichton Mt Newton on December 21, 2020. Those are station measurements from NOAA's daily records, 1998 to 2025, not official state records. By area the largest place is Roche Harbor, about 4 square miles.
About San Juan County weather
The map on the Now tab shows every San Juan County town's current temperature from our own server, one dot per town. Tap any dot, or type a town above, for that town's full forecast.
What the weather is usually like
Across the 2 San Juan County towns with station normals, the warmest month is August, when the day usually reaches 73°F, and the coldest is January, when the night usually falls to 36°F. January is the wettest, with rain on about 16 days.
Means of the 1991 to 2020 station normals serving these towns, as published by NOAA; each town's page carries its own.
Where these numbers come from
- Current conditions and forecast: NOAA forecast grids decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
- Records: computed by myweatherrock from NOAA GHCN-Daily station records at the stations serving these towns. Measurements, not estimates.
- Warnings and alerts: the National Weather Service, passed through unchanged.
San Juan County weather records
Measured at the NOAA stations serving these towns, daily records 1998 to 2025. Station extremes, not official state records.
Common questions about San Juan County weather
- What is the hottest temperature recorded at a San Juan County station?
- 101°F at Friday Harbor Ap on June 28, 2021, in the NOAA daily station records myweatherrock holds (1998 to 2025).
- What is the coldest temperature recorded at a San Juan County station?
- 8°F at Friday Harbor Ap on December 20, 2008.
- What is the most rain a San Juan County station has measured in one day?
- 2.5 inches at Friday Harbor Ap on December 21, 2020.
- What is the biggest one-day snowfall at a San Juan County station?
- 25.59 inches at Saanichton Mt Newton on December 21, 2020.
- How many San Juan County towns have a weather page here?
- 2: 1 towns, 1 census-designated places. Each page carries current conditions, the hourly timeline, the ten day outlook, radar, and where a station sits close enough, measured records.
- Where does the San Juan County forecast come from?
- NOAA forecast grids (the National Weather Service digital forecast, the National Blend of Models, HRRR and GFS) decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
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