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Phoenix, Arizona has a hot desert climate (Köppen BWh) with roughly 299 sunny days and just 183mm (7.22 inches) of rain a year, almost all of it falling during the July-to-September monsoon. July is the hottest month, averaging a high of 41°C (106°F), while January is the coolest at 19°C (67°F). This guide breaks down Phoenix weather by month so you can plan around the heat, which is the one factor that dominates every trip here. For related guidance, see the best time to visit Phoenix guide. For related guidance, see the things to do in Phoenix guide.
Phoenix Weather by Month: Climate at a Glance
Phoenix sits in the Sonoran Desert at 331m (1,086 ft) elevation, in the Salt River Valley. The defining feature is the summer heat: from June through early September, daytime highs stay above 38°C (100°F), and overnight lows often fail to drop below 27°C (80°F). Winter is the opposite, with highs near 19°C to 22°C (67°F to 71°F) and dry, sunny days. The annual rainfall of 183mm comes in two bursts, winter storms from December to March and the summer monsoon from late June through mid September. For related guidance, see the Phoenix events and festivals guide. For related guidance, see the Phoenix neighborhoods guide.
Phoenix Weather by Month: Temperature and Rainfall Table
| Month | Avg High | Avg Low | Rain (mm) | Sunshine (hrs) |
|---|---|---|---|---|
| January | 19°C / 67°F | 8°C / 46°F | 22mm | 256 |
| February | 22°C / 71°F | 9°C / 49°F | 22mm | 257 |
| March | 26°C / 78°F | 12°C / 54°F | 21mm | 318 |
| April | 30°C / 86°F | 16°C / 61°F | 6mm | 353 |
| May | 35°C / 95°F | 21°C / 70°F | 3mm | 400 |
| June | 40°C / 104°F | 26°C / 79°F | 1mm | 407 |
| July | 41°C / 106°F | 29°C / 84°F | 21mm | 378 |
| August | 40°C / 104°F | 28°C / 83°F | 23mm | 360 |
| September | 37°C / 99°F | 24°C / 76°F | 15mm | 327 |
| October | 31°C / 88°F | 18°C / 64°F | 15mm | 314 |
| November | 24°C / 75°F | 11°C / 52°F | 17mm | 261 |
| December | 19°C / 66°F | 7°C / 45°F | 22mm | 244 |
Phoenix Weather by Month: Winter (December to February)
Winter is the reason Phoenix fills with snowbirds and spring-training fans. Daytime highs hold between 19°C and 22°C (66°F to 71°F), so a light jacket is all you need, and the sky stays clear on most days. Overnight lows drop to 7°C to 9°C (45°F to 49°F), and a handful of nights each winter dip near freezing in outer suburbs like Cave Creek and Queen Creek. December and February each average 22mm of rain, spread over two or three cloudy days tied to Pacific storms. For related guidance, see the where to stay in Phoenix guide. For related guidance, see the Phoenix travel tips guide.
Phoenix Weather by Month: Spring (March to May)
March through April is the most comfortable stretch of the year, with highs climbing from 26°C (78°F) to 30°C (86°F) and almost no rain. This is prime hiking weather for Camelback Mountain and the Desert Botanical Garden, and it coincides with Cactus League baseball from late February to late March. By May the heat turns on, reaching 35°C (95°F) by the end of the month, and the first 38°C (100°F) day usually arrives by mid May. May is also the driest month at just 3mm of rain.
Phoenix Weather by Month: Summer and the Monsoon (June to September)
Summer is brutal and dry at first, then turns humid and stormy. June averages a high of 40°C (104°F) and July peaks at 41°C (106°F), with 18 to 20 days a month at or above 38°C (100°F). The urban heat island keeps overnight lows near 28°C to 29°C (83°F to 84°F), so there is little relief after dark. Around the first week of July the North American monsoon arrives, pulling moisture up from the Gulf of California and the Gulf of Mexico. July and August each get 21mm to 23mm of rain in brief but intense afternoon thunderstorms that can produce dangerous flash flooding and dust storms called haboobs. Expect lightning and downburst winds more than steady rain.
Phoenix Weather by Month: Autumn (October to November)
Autumn is the mirror image of spring and just as pleasant. October still reaches 31°C (88°F) during the day but drops to 18°C (64°F) at night, and by November the high is 24°C (75°F). Monsoon rain tapers off by the end of September, and October and November together average only 32mm. This is a strong shoulder season for cheaper hotels and comfortable pool weather, before the winter crowds return. See the best time to visit Phoenix for how these seasonal patterns translate into good booking windows.
