Tanoak grows in a climate broadly classified as humid. Annual precipitation, however, is seasonal and varies from 1020 to 2540 min (40 to 100 in). Some precipitation is snow. Summer and early fall are dry and the winter rainy. From June through September rainfall totals less than 25 min (1 in) a month. In fact, precipitation during these months amounts to only 5 percent of the year's total. Most of the precipitation-about 70 percent-falls between November and February.
Average mean daily temperatures range from 2° to 6° C (36° to 42° F) during January and 16° to 23° C (60° to 74° F) in July. The season free of killing frosts begins between March 8 and April 30 and ends between October 20 and November 20, varying in length between 160 and 249 days. Over a 30-year period the maximum temperature recorded at 183 in (600 ft) elevation in the center of tanoak's area of maximum development was 45° C (113° F).