Arizona’s Monsoon

Arizona resides within the northern extent of the North American Monsoon. The monsoon season typically begins in early June when active thunderstorms build in central and southern Mexico and then move toward the International Border into Arizona. The monsoon is a season where the dry, westerly winds that typically persist through fall, winter and spring shift to moist, southerly winds. The incoming monsoonal moisture helps build thunderstorm activity across the state.
Terminology: The term “monsoon” refers to a seasonal time of year where thunderstorms are more likely to occur. A monsoon is NOT a thunderstorm, but the monsoon season can help build thunderstorms.
Monsoon thunderstorm activity accounts for roughly half of the annual precipitation in central and northern Arizona, and two-thirds to three-fourths of the annual precipitation in southern Arizona. The short-lived, intense monsoon thunderstorms can often cause flash flooding in areas of steep terrain, low-lying roads, or normally dry washes. Lightning, hail, dust storms, and strong winds are common during the monsoon season.
Basics of the Arizona Monsoon
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Outlook Day 1 (today) |
Outlook Day 2 (tomorrow) |
Outlook Day 3 (next day) |
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Total Monsoon Precipitation (to date)
Average Daily Dewpoint
Arizona Regional WRF Model Forecasts
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Total Precipitable Water
500mb height, wind, vorticity
NAM – HRRR – GFS
700mb height, wind, relative humidity
NAM – HRRR – GFS
850mb temperature, relative humidity, wind
NAM – HRRR – GFS
2021 Monsoon Review
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NWS Southern Arizona Dust Storm Workshops
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Monsoon Literature
Arizona and the North American Monsoon System Crimmons
Understanding the Southwest Monsoon Guido
Long Term Changes of Transient Inverted Troughs Lahmers, et al