Get to Know Monsoon
Arizona's monsoon starts June 15 and ends September 30, although the seasonable wind shift that brings moisture up from Mexico can start any time from early to mid-summer. Use this page to track our annual rainy season.
A high-pressure zone starts it all
Summer rains typically start in late June to early July, when a zone of high atmospheric pressure settles near the intersection of Arizona, Utah, Colorado, and New Mexico. Prevailing westerly winds north of this “Four Corners” high-pressure zone help it spin clockwise, pulling moisture mostly from the Pacific Ocean but also from the Gulf of Mexico north into the western U.S.
Read more in an in-depth look at monsoons [PDF] by Arizona Cooperative Extension Specialist Mike Crimmins, Ph.D.
Climate Outlook
This University of Arizona project offers a look at what to expect in the Southwest’s climate.
Regional Maps
U of A maps updated daily with rainfall totals, number of rain days, and rainfall total compared to average.
Arizona Maps
Updated daily showing total precipitation and rain event intensity and frequency across the state.
Real-Time Weather
Get real-time rainfall and temperature data from monitoring sites across Arizona and New Mexico.
Greenness Tracker
Check back to track Arizona’s "green up” as monsoon rain sparks an annual explosion of plant life.
Citizen Science
Check rainfall in your neighborhood or sign up to report rainfall from your back yard.
Track Drought
Check the Standard Precipitation Index (a measure of drought) for your area in near real-time.
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