Phoenix is hot desert, and the heat is the whole story. From late May through September the city averages well over 100 days a year at or above 100°F, and nighttime lows in July often don't drop below 90°F in the urban core thanks to the heat-island effect. The monsoon arrives in July: a daily pattern of building cumulus, blowing dust, and intense but short-lived thunderstorms that supply most of the year's modest rain. Winters are nearly perfect — sunny, dry, daytime highs in the 60s and 70s — which is why so many people winter here.
Climate and Average Weather Year Round in Phoenix
Year-round temperature
In Phoenix, the warmest months are June through September, with average daily highs between 100°F and 107°F. The coldest stretch runs December through February, with highs between 66°F and 71°F and overnight lows reaching 45°F.
Rainfall through the year
Rainfall in Phoenix averages 0.6 in per month over the long run. August is the wettest at 0.9 in, while June is the driest at 0.0 in.
Days at 90 °F or hotter
Phoenix averages 171.4 days per year at 90 °F or hotter. The hottest year on record saw 192 such days (2017); the coolest just 60 (2026).
Precipitation this year
As of May 28, Phoenix has received 0.3 in of precipitation this year — 89% below the long-term normal for this point in the year (2.9 in).