Elevation varies from 1,000 feet to 6,000 feet. Precipitation increases as the elevation increases in an easterly direction. Annual precipitation is between 10 to 20 inches over most of the agricultural section increasing to 40 inches or more in the higher elevations of the Blue Mountains. The average winter season snowfall varies from 20 to 40 inches. Snow can be expected in November and to remain on the ground from periods ranging from a few days to two months between the first of December and March. Snowfall and the depth on the ground increase along the slopes of the mountains.
The average January maximum temperature is near 34° F in the Palouse Hills and 38° in the Snake and Walla Walla River valleys. The average minimum temperature varies from 20° to 25° F. Minimum temperatures between 0° and -15° F are recorded on a few nights each winter and temperatures ranging from -25° to -35° F have been recorded. In July, the average maximum temperature is in the upper 80's and the minimum is in the mid –50s. Maximum temperatures usually reach 100° F on a few afternoons and temperatures from 105° to 112° F have been recorded.