Climate change in Walla Walla County, Washington
Since 1979, Walla Walla County, Washington has warmed 1.9°F, with 11 more days above 90°F, about the same number of nights above 70°F and 15% less precipitation a year.
- Average temperature: +1.9°F
- Summer highs (Jun–Aug): +3.6°F
- Winter lows (Dec–Feb): +1.4°F
- Precipitation: −15%
- Wettest day of the year: −18%
- Longest dry spell: +24 days
- Days above 90°F: +11 days
- Nights above 70°F: +0 days
- Freezing nights: −1 days
- Frost-free season: +20 days
- Muggy days: +0 days
- Summer heat index (Jun–Aug): +2.8°F
- Extreme fire-weather days: +22 days
Changes follow the trend line through every year from 1979 to 2025. Data: NOAA nClimGrid-Daily; humidity from gridMET, adjusted to airport observations.