The Tri-Cities are in a semi-arid climate,receiving an average of 7 to 8 inches (180 to 200 mm) of precipitation every year. Winds periodically exceed 30 mph (48 km/h) when "Chinook wind" conditions exist. While there are an average 225 clear days every year, these are mainly between April 1 and November 1.

Temperatures range from as low as −25 °F in the winter to as high as 110 °F  in the summer, and even reached 115 °F in July 2006. The region only receives occasional snow most years, but has received as much as 50 inches in rare years. Due to the semi-arid climate and subsequent large amounts of sand, frequent winds can create dust storms.  Irrigation water is available for agricultural crops because of the proximity of the Yakima and Columbia rivers. 

The Cascade Mountain Range to the west contributes to the semi-arid climate, because of the rain shadow phenomenon. The region's arid climate results in a shrub-steppe ecosystem.  Just west of Richland, the Fitzner/Eberhardt Arid Lands Ecology Reserve was established to study the unique plants and animals found in the local shrub steppe ecosystem. It is the largest tract of shrub-steppe ecosystem remaining in the U.S. state of Washington.

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