Tropical Storm Hilary Hits California and Southwest

Updated August 21, 2023 11 a.m. EST

• Southern California was hit with heavy rain over the weekend as Hilary, now a post-tropical cyclone, swept the region. A flash flood warning was in effect in Los Angeles County and parts of Nevada until Monday morning. Meteorologists continue to warn of life-threatening conditions. 
• Around 40,000 residents were without power, but there have been no immediate reports of death or injuries. 
• On Sunday, an unrelated 5.1-magnitude earthquake struck California. An estimated 12 million people were affected.

What's the story?

• Hurricane Hilary, a Category 4 storm, is heading toward the Southwest and could bring a year's worth of rain to Arizona, California, and Nevada. Almost 26 million people in the region are under flood watches.
• The hurricane is expected to lose strength as it makes landfall, but the National Weather Service warned that it would result in "significant impacts." Officials have also issued hurricane watches and tropical storm warnings for Baja California and northwest Mexico.

How strong is Hilary?

• As of Friday morning, Hilary is a powerful Category 4 hurricane, with wind gusts of up to 145 mph, about 400 miles south of Cabo San Lucas, Mexico. Hilary strengthened from a tropical storm to a hurricane in just 24 hours, a rapid intensification.
• There is a chance that Hilary will become the first Category 5 hurricane of the season before it enters colder water and loses strength. Hilary is expected to weaken into a Category 3 hurricane by late afternoon Saturday and diminish into a tropical storm by Sunday.
• It is expected to make landfall on Saturday morning and fully hit the region by Sunday and into early next week. Hilary is more likely to make landfall in Mexico and cross into California.
• If it makes landfall in California as a tropical storm, it will be the first time this has occurred in the state since 1939. 

Flooding risks

• High-risk heavy rainfall could increase the potential for flooding. These events are issued less than 4% of days per year but are responsible for 83% of all flood-related damage and 39% of all flood-related deaths.
• Parts of southern California and Nevada could receive 3 to 5 inches of rain, with desert regions like Palm Springs and the Sierra Nevadas receiving up to 10 inches. Arizona and Southwest Utah could receive 1 to 3 inches.
• The National Weather Service in Los Angeles has also warned of the potential for dangerously high waves, rip currents, and coastal flooding.
• Samantha Connolly, a National Weather Service meteorologist, said: 

"The combination of heavy rainfall, the potential for flash flooding and strong winds could very well make this a high-impact event for Southern California." 

Are you worried about extreme weather?

—Emma Kansiz

(Photo credit: NOAA National Hurricane Center)