Aug 18, 2023 - Climate

Hurricane Hilary could bring rainfall and cooler temps to the Valley

Rain with a saguaro cactus in the foregound.

Photo: Mario Tama/Getty Images

Phoenix finally snapped its rainless streak , with high temperatures under 100° for the first time since June 13.

Why it matters: Measurable precipitation hadn't been recorded at Sky Harbor since March 22, making it the second longest rainless stretch on record.

What's happening: National Weather Service meteorologist Austin Jamison tells us the Valley could see some traditional monsoon storms as early as tonight and will likely benefit from a hurricane strengthening off the coast of western Mexico later this weekend and early next week.

The big picture: Hurricane Hilary, now a Category 4 storm, is poised to bring flooding rains into southern California, Nevada and Arizona, Axios' Andrew Freedman reports.

Reality check: Don't expect hurricane-level rainfall in metro Phoenix, Jamison says. The storm will weaken significantly by the time it arrives in Arizona.

  • Yes, but: The humidity and moisture the storm will bring into the state is likely to trigger thunderstorms in the Valley and cool temperatures.

The intrigue: The NWS forecast office in Phoenix said Wednesday that the amount of atmospheric water vapor surging into the Southwest ahead of the storm may reach levels "almost never experienced this time of year."

Context: Human-caused climate change is leading to more frequent and intense extreme precipitation events and causing wetter tropical storms and hurricanes.

  • It is also making rapid intensification of such storms more common.
  • It's extremely rare, but not unheard of, for a tropical storm or hurricane to make landfall in Southern California, because the region is protected by relatively cool ocean waters.

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