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When Is Monsoon Season in Arizona? Dates and Home Prep

Arizona's monsoon season officially runs June 15 through September 30. Here are the dates, the rain normals by county, and what to check on your roof, AC, pool and power before the first storm.

Updated Oct 22, 2026

When monsoon season runs

The official monsoon season runs from June 15 through September 30.[22] Arizona's Emergency Information Network gives the same window, mid-June through the end of September.[21]

That window is a calendar definition, not a promise of rain.

In northern Arizona, monsoonal moisture typically reaches the region around the first week of July.[22] Across the Southwest, the monsoon typically arrives in early July, with mountain ranges helping focus daily thunderstorm development.[23]

Timeline

The monsoon season calendar

  1. June 15

    Official season begins

  2. First week of July

    Moisture typically reaches northern Arizona

  3. September 30

    Official season ends

Outlooks for 2026 change as the season approaches. Check the National Weather Service Tucson 2026 monsoon outlook rather than relying on any forecast repeated elsewhere.[24]

Thunderstorm clouds over a desert mountain range
Monsoon thunderstorm clouds building over a desert landscape

How much rain each county gets from July through September

These rows cover July through September only, not the full June 15 to September 30 season. Each is a NOAA 1991-2020 normal at a single station for that county, not a county average.

County Station Jul-Sep rain
Cochise Bisbee 1Wnw 10.04 in[2]
Santa Cruz Nogales 6 N 9.73 in[13]
Coconino Flagstaff Pulliam Airport 7.49 in[3]
Yavapai Prescott 7.11 in[14]
Gila Globe #3 5.8 in[4]
Pima Tucson International Airport 5.51 in[11]
Greenlee Duncan 5.07 in[6]
Apache Saint Johns 5.02 in[1]
Graham Safford Ag Ctr 4.27 in[5]
Pinal Casa Grande Nm 3.06 in[12]
Navajo Winslow Muni Airport 2.92 in[10]
Mohave Kingman Mohave Co Airport 2.7 in[9]
Maricopa Phoenix Sky Harbor International Airport 2.41 in[8]
Yuma Yuma Mcas 1.12 in[15]
La Paz Parker 1.02 in[7]

At these stations, Cochise County is the wettest and La Paz County the driest.

Phoenix sits near the low end, with a July normal high of 106.5 F at Sky Harbor.[8] The full county comparison, with temperatures, is on the Arizona temperature and monsoon rain by county page.

Dust and wind arrive before the rain

Strong monsoon winds can create downbursts and dense blowing dust that may cut visibility to near zero in seconds.[21] Monsoon hazards include debris flows, lightning, downburst winds and dust storms.[24]

The National Weather Service also publishes wind and dust storm safety guidance.[17]

For what dust does to a house, read Haboobs in Arizona: What Dust Storms Do to Your Home.

Prepare the roof, the AC, the pool and the power

Each trade below has a hub with permit and licensing rules. Verify any contractor on the ROC contractor search before you hire.

Where the weather service posts warnings

Four National Weather Service offices cover Arizona. Use the one that serves your county.

Office Counties Pages
NWS Flagstaff Apache, Coconino, Navajo, Yavapai Monsoon[22], dust storms[17]
NWS Tucson Cochise, Graham, Greenlee, Pima, Santa Cruz Monsoon safety[18]
NWS Phoenix Gila, La Paz, Maricopa, Pinal, Yuma Monsoon and dust[20], heat[19]
NWS Las Vegas Mohave Dust storms[17], heat[16]

The Flagstaff and Las Vegas offices have no heat or dust page of their own, so those links go to the national safety pages.

The state's Monsoon Awareness page adds hazard guidance.[21]

Quick answers

When is monsoon season in Arizona?

The official season runs from June 15 through September 30.

When does the rain usually start?

Moisture typically reaches northern Arizona around the first week of July, and the Southwest monsoon typically arrives in early July.

What hazards come with the monsoon?

Debris flows, lightning, downburst winds and dust storms.

Sources

  1. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Saint Johns (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00027435&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  2. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Bisbee 1Wnw (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00020775&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  3. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Flagstaff Pulliam Airport (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00003103&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  4. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Globe #3 (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00023501&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  5. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Safford Ag Ctr (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00027390&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  6. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Duncan (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00022754&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  7. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Parker (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00026250&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  8. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Phoenix Sky Harbor International Airport (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00023183&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  9. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Kingman Mohave Co Airport (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00093167&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  10. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Winslow Muni Airport (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00023194&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  11. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Tucson International Airport (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00023160&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  12. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Casa Grande Nm (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00021314&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  13. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Nogales 6 N (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00025924&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  14. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Prescott (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USC00026796&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  15. NOAA National Centers for Environmental Information. "NOAA 1991-2020 Climate Normals, Yuma Mcas (monthly normals)." https://www.ncei.noaa.gov/access/services/data/v1?includeStationName=1&format=csv&stations=USW00003145&dataset=normals-monthly-1991-2020&dataTypes=MLY-TMAX-NORMAL,MLY-PRCP-NORMAL. Accessed October 21, 2026.
  16. National Weather Service. "National Weather Service: extreme heat safety." https://www.weather.gov/safety/heat. Accessed October 21, 2026.
  17. National Weather Service. "National Weather Service: wind and dust storm safety." https://www.weather.gov/safety/wind-dust-storm. Accessed October 21, 2026.
  18. National Weather Service. "NWS Tucson monsoon safety (heat, thunderstorm and dust storm)." https://www.weather.gov/twc/monsoonsafety. Accessed October 21, 2026.
  19. National Weather Service. "NWS Phoenix heat safety." https://www.weather.gov/psr/heat. Accessed October 21, 2026.
  20. National Weather Service. "NWS Phoenix dust storm and monsoon safety." https://www.weather.gov/psr/MonsoonSafety. Accessed October 21, 2026.
  21. Arizona Emergency Information Network. "Monsoon Awareness." https://ein.az.gov/monsoon-awareness-0. Accessed October 21, 2026.
  22. National Weather Service, Flagstaff. "Northern Arizona Monsoon Season." https://www.weather.gov/fgz/monsooninfo. Accessed October 21, 2026.
  23. National Weather Service, Tucson. "Monsoon Information Page." https://www.weather.gov/twc/Monsooninfo. Accessed October 21, 2026.
  24. National Weather Service, Tucson. "2026 Arizona Monsoon Outlook One Pager." https://www.weather.gov/media/twc/monsoon/2026ArizonaMonsoonOutlookOnePagerEnglish.pdf. Accessed October 21, 2026.