Washington County Climate
Washington County, Idaho
Avg Annual Temp
51.9°F
Annual Precip
16.6"
Annual Snowfall
—
Extreme Heat Days
63.1
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Washington County Weather
Warmest of the Region
Washington County averages 51.9°F annually, coming within two degrees of the national median. This makes it one of the more temperate climates in the Pacific Northwest interior.
Leading Idaho in Temperature
At 51.9°F, Washington County is significantly warmer than the Idaho state average of 46.5°F. It ranks as one of the warmest counties in the state.
Consistent State Rainfall Patterns
The county sees 16.6 inches of precipitation, almost matching the Idaho average of 17.0 inches. It is much drier than the mountainous counties to its immediate east.
Intense Summer Heat Waves
Summers are very hot, featuring 63 days per year with temperatures at or above 90°F. Winters are moderate for the state, averaging 30.8°F between December and February.
Cooling is the Priority
Residents must maintain robust HVAC systems to handle two full months of extreme summer heat. While snowfall data is limited, the focus remains on summer cooling and water management.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.