I'm tellin' ya - if you wan sunshine, come to PHX - they don't call it, "The Valley of the Sun," for nothin'...
Phoenix has an arid climate, and its average annual maximum temperature is the highest of any major US city. In fact, out of the world's large urban areas, only some cities around the Persian Gulf, such as Riyadh, Saudi Arabia, and Baghdad, Iraq, and India such as Jaipur have higher average summer temperatures. The temperature reaches or exceeds 100 °F (38 °C) on an average of 89 days during the year, including most days from early June through early September. On June 26, 1990, the temperature reached an all-time high of 122 °F (50 °C). Overnight lows greater than 80 °F occur frequently each summer, with the average July low being 81 °F and the average August low being 80 °F. The all-time highest low temperature was 96 °F (36 °C), which occurred on July 15, 2003.
The dry desert air makes the hot temperatures more tolerable early in the season, but the influx of monsoonal moisture, which generally begins in early July and lasts until mid-September, raises humidity levels and discomfort due to mugginess. For the most part, the winter months are mild.
Phoenix averages 85% of possible sunshine and receives scant rainfall, the average annual total at Phoenix Sky Harbor International Airport being 8.3 inches (210 mm). March is the wettest month of the year (1.07 inches or 27 mm) with June being the driest (0.09 inches or 2 mm). Although thunderstorms are possible at any time of the year, they are most common during the monsoon from July to mid-September as humid air surges in from the Gulf of California. These can bring strong winds, large hail, or rarely, tornadoes. Winter storms moving inland from the Pacific Ocean occasionally produce significant rains but occur infrequently. Fog is observed from time to time during the winter months.
On average, Phoenix has only 5 days per year where the temperature drops to or below freezing. The long-term mean date of the first frost is December 15 and the last is February 1; however, these dates do not represent the city as a whole because the frequency of freezes varies considerably among terrain types and elevations. Frequently, outlying areas of Phoenix will see frost, however, the airport does not. The earliest frost on record occurred on November 3, 1946, and the latest occurred on April 4, 1945. The all-time lowest temperature in Phoenix was recorded at 16 °F (-8.8 °C) on January 7, 1913.