Chief Joseph Dam, WA Climate

Climate Insight: Chief Joseph Dam, WA

In Chief Joseph Dam, Washington, the NOAA 1991–2020 climate normals put the annual average temperature at 51°F, ranging from a mean daily high of 63°F to a mean daily low of 39°F. July is typically the warmest month of the year, while January is the coldest. As thirty-year averages computed from station USC00451400, these numbers smooth out year-to-year noise into a working baseline for a typical month.

Rainfall (and snow, where it falls) shapes day-to-day life here as much as temperature does. Chief Joseph Dam sees about 10.8 inches of precipitation a year, with 27.9 inches typically falling as snow. The frost-free season averages 168 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 26 and the first fall freeze near October 11. On the energy side, 5,874 heating degree days and 794 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Chief Joseph Dam scores 49/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. Use the monthly tables above to plan around specific windows, shoulder seasons for mild highs and lows, peak summer for July-driven heat, or deep winter for January-driven cold. All figures here are thirty-year averages: any single year may run warmer, wetter, drier, or cooler than the normal, so treat them as planning guidance rather than forecasts.