Island County Climate
Island County, Washington
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
51.2°F
Annual Precip
20.8"
Annual Snowfall
4.0"
Extreme Heat Days
0
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
8b
Minimum winter temperature range for plant survival
1,542
Favors cool-season crops
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Island County
Climate Verdict
Island County has a mild, with an average annual temperature of 51.2°F, semi-arid conditions with only 20.8 inches of annual precipitation, rare extreme heat with only 0.3 days above 90°F annually, light snow averaging 4.0 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are mild, with January temperatures averaging 42.0°F. summers are pleasantly cool with July averaging 61.5°F. The climate is remarkably stable year-round, with only a 19°F difference between January and July. December is typically the coldest month and August the warmest.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Island County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Island County closely matches the Washington statewide average temperature of 49.9°F, it is also noticeably drier, receiving 17.7 inches less precipitation than the state average, the county experiences 17.69276705276705 fewer extreme heat days than the state average.
Climate Profile
About Island County Weather
Tempered by the Salish Sea
Island County’s 51.2°F average is tempered by the surrounding sea, keeping it cooler than the national median. It enjoys a mild maritime climate with moderate rainfall of 20.8 inches.
Island Rain Shadow Comfort
It is slightly warmer than the 49.9°F state average but much drier than the 38.5-inch state norm. Its location in the rain shadow of the Olympics provides a more Mediterranean feel.
Drier Than the Outer Coast
Island County is much drier than Grays Harbor, receiving only a fifth of the rainfall found on the outer coast. It also lacks the extreme heat seen in the eastern counties, recording zero days above 90°F.
Stable Temps and No Heat
The climate is remarkably stable, with summers averaging 60.4°F and winters averaging 42.2°F. Snowfall is minimal at 4.0 inches, and extreme heat is virtually non-existent.
Light Layers and Sea Breezes
Residents can skip the heavy-duty cooling systems since the county records no days over 90°F. Focus on wind-resistant apparel and light layers to manage the breezy, temperate coastal conditions.
Frequently Asked Questions
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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.