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3.5.2 Climate and Temperature As is typical of areas in the lee of large coastal mountain ranges, the Yakima River Basin is generally arid. Precipitation varies with elevation and distance from the Cascades, from 150 inches annually at the Cascade crest to 10 inches at the Columbia River. Disparities in precipitation rates from one area to another affect runoff rates and the character of rivers in different drainages, which influence flooding and land -use potential. Summers in Kittitas County tend to be dry; approximately two-thirds of the county's precipitation occurs between October and April, with much in the form of snow. In the winter, considerable snow often accumulates in the higher elevations. In the Kittitas Valley, snow season generally ranges from November through February, with significant variation from one season to the next. Because of the variation in elevation, temperatures vary greatly in the Yakima River Basin. in the Kittitas Valley, summers tend to be hot, with wide divergent fluctuations, and mild to severe winters. Data are scarce for higher elevations; however, those areas are generally characterized by cool summers and cold winters. For example, in the Subalpine Fir forest zone, which extends from approximately 2,000 feet to the timberline, mean July temperatures in the range of 55°F to 65°F can be expected. 3.5.2.1 Wind During the summer, pressure is higher on the western side of the Cascades and lower over the heated basin of eastern Washington, with the pressure difference increasing during the day as temperatures soar over eastern Washington. Air accelerates from high to low pressure and it finds the weakest location called Stampede Gap, where the terrain is only 3,000 to 4,000 feet high. Air accelerates through the gap and spreads out over the Kittitas Valley, with northwest winds on many summer days gusting to 30 to 40 miles per hour (Mass 2009). The prevailing wind is from the northwest. The daily wind speed averages 8 to 10 miles per hour in the spring and summer, although wind speeds up to 20 to 30 miles per hour are not uncommon in the Kittitas Valley. Community Wildfire Protection Plan 19 September 2018