A majority of precipitation occurs in the winter months (Nov - March) due to the yearly dip of the jetstream bringing Pacific storms. Temperatures in summer are very warm to hot. The July average of means that 100-degree days are a common occurrence in a typical summer. The elevation, aridity, and clear skies allow intense radiative cooling, even in midsummer. This means hot days are followed by mild evenings. Southerly monsoon rains from mid-July through September bring thunderstorms, increased dew points, and flash flooding.