The warning was in effect for Riverside County and northeastern San Diego County, according to the National Weather Service. The warning includes Indio, southeastern Palm Springs and Coachella.
“Life threatening flash flooding of creeks and streams, urban areas, highways, streets and underpasses,” is possible according to the warning.
Rain from Kay had begun falling Friday in far Southern California, including San Diego, and far southwest Arizona, including Yuma, as flash flooding risks increase.
A flash flood warning was also in effect for southwestern Imperial County, where up to 1.5 inches of rain had fallen.
Flood watches cover more than 6 million people across Southern California, including Palm Springs, Riverside and Barstow; southern Nevada, including Las Vegas; and western Arizona, including Yuma, Lake Havasu City and Kingman.
“Imperial Valley farmers are in the middle of preparing their lands for the planting season, so a half an inch to 1 inch of rain will cause damage and delays to their schedule,” said Robert Schettler, a spokesperson for the Imperial Irrigation District.
While the damage Kay will leave behind is uncertain, the storm is expected to leave in its trail more moderate temperatures as it turns away from the US West Coast and pushes out into the Pacific on Saturday.
Meantime, wildfires also continue to ravage Northern California, while Oregon faces heightened fire danger as similar strong winds from the east blow in from a separate weather system.
High temperature and rain records could fall
With triple-digit temperatures continuing Friday for much of California, record highs are expected to be set before Kay’s cool-down takes hold.
Behind the heat, fast, heavy deluges also could rewrite record books. Two to 4 inches is expected over 36 hours on Friday and Saturday at Imperial County Airport, which on average gets 2.38 inches of rain each year. If Imperial receives more than 3 inches of rain, it will make this month its wettest September on record; the previous wettest September was in 1976.
In Palm Springs, which typically sees 4.61 inches of rain annually, 2 to 4 inches are forecast. Three inches at Palm Springs would put this month in the top three wettest Septembers for the city, where the average September rainfall is 0.24 inches.
And Yuma could see 1.5 inches — which would make 2022 the wettest September since 2009. The city’s average September rainfall is 0.68 inches.
Fire woes impact California and Oregon
Oregon, meanwhile, faces strong winds from the east that will increase fire danger across the state due to a weather system separate from Kay.
Utility companies Pacific Power and Portland General Electric announced they may proactively turn off power in some high-risk areas to reduce the risk of fire.
The outages would be implemented “in a limited, high-risk area to help reduce the risk of wildfire and to help protect people, property and the environment,” Portland General Electric said in a release. The move could impact about 30,000 customer meters in the Portland and Salem, Oregon, area, the utility said.
CNN meteorologists Taylor Ward and Allison Chinchar, and CNN’s Christina Maxouris, Steve Almasy, Stephanie Elam, Ella Nilsen, Paradise Afshar and Chris Boyette contributed to this report.