Pasco Tri Cities, WA Climate

Climate Insight: Pasco Tri Cities, WA

In Pasco Tri Cities, Washington, the NOAA 1991–2020 climate normals put the annual average temperature at 53°F, ranging from a mean daily high of 66°F to a mean daily low of 40°F. July is typically the warmest month of the year, while December is the coldest. As thirty-year averages computed from station USW00024163, these numbers smooth out year-to-year noise into a working baseline for a typical month.

Pasco Tri Cities averages 7.6 inches of precipitation a year, predominantly as rainfall, and that matters as much to daily life here as temperature does. The frost-free season averages 167 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 27 and the first fall freeze near October 11. As for energy demand, 5,011 heating degree days and 788 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Pasco Tri Cities scores 44/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above turn that into a planning tool: expect the mildest highs and lows in the shoulder seasons, July-driven heat at the peak of summer, and December-driven cold at the depth of winter. Every number here is a thirty-year average, not a forecast, so any given year can and does run warmer, cooler, wetter, or drier than the normal.