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Walnut Creek, Contra Costa County, California, United States (37.90207 -122.06187)
Walnut Creek's warm summer Mediterranean climate (Köppen climate classification Csb) is typical of California's interior valleys. In summer, high pressure is in control of the region, leading to almost unbroken sunshine and virtually no precipitation. Days start out cool but quickly warm up, with high temperatures normally in the 80s Fahrenheit (27 to 32 °C). Temperatures of 100 °F (38 °C) or hotter occur numerous times during heatwaves, however. In the winter, the jet stream moves far enough south so that Pacific storms can reach Walnut Creek, bringing much-needed rain – average annual rainfall approximates 20 inches (510 mm), with slight variations occurring in microclimates based on elevation and topography. During particularly cold storms, snow falls on the peak of nearby Mount Diablo, but snow in the valley floor is very rare. There are also plenty of clear, mild days in winter, often with morning frost. The climate allows for the successful cultivation of many plants and crops, being warm enough for citrus yet cold enough for apples. The Ruth Bancroft Garden is a renowned botanical garden that showcases the diversity of plants that can be successfully grown.