The most important influence on the climate in Washington is the Cascade Moutain range, which separate Seattle from the rest of the state. On the western side, there is a great deal of rain and temperatures are cooler. But on the eastern side, where the columbia valley is located, there is very little rain, and the climate is quite arid, almost desert-like. Because of the dryness, irrigation is usually required in this area. Warm temperatures during the day, and cool temperatures at night help preserve acidity. Because of its northerly latitude, Washington also receives about 2 hours of sunlight more than California per day. Because of cold winters and sandy soils, Washington has never had a problem with Phylloxera.