A storm that formed off the Pacific shores of Mexico moved up the coast of the Baja California peninsula and brought heavy winds and rain into California, which has already been coping with extreme heat, wildfires and drought.
Tropical Storm Kay, which briefly reached hurricane status on Thursday became a post-tropical cyclone on Friday night, caused heavy rain and flooding in Mexico. Strong winds and rainfall were spreading into Southern California and Arizona on Friday, the National Weather Service said.
By 11 p.m. Eastern time, Kay no longer possessed the strength of a tropical storm, though forecasters warned that it could still produce heavy rains and strong winds in northern Baja California and Southern California.
The storm was about 145 miles southwest of San Diego and moving northwest at 8 miles per hour, with maximum sustained winds of 40 m.p.h., the National Hurricane Center said.
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The remnants of the storm were expected to move offshore on Saturday.
So far, the rainfall, humidity and cloud cover were helping firefighters in Hemet, Calif., gain control of the Fairview Fire, which has burned more than 28,000 acres and continues to threaten 10,000 structures. The fire was 40 percent contained by Friday night, a sharp increase from the 5 percent earlier in the day.
Fire officials were initially unsure if the weather would help or hurt fire efforts and grew worried about aircrafts that spray water or fire retardant would be grounded because of the winds.
But by Friday evening, state fire officials said that the worst they had feared had not come to pass.
Kay could still dump 6 to 10 inches of rain, with some areas seeing up to 15 inches in Baja California. Southern California could see 2 to 4 inches of rain, with parts getting 8 inches. Heavy rainfall is also possible in southwest Arizona.
Officials are still concerned it could create floods and debris flows through charred foothills and canyons, or even mudslides.
Gusts of up to 109 miles per hour were recorded on a mountain peak east of San Diego, according to the National Weather Service, while flash flood warnings were in effect for deserts near the border with Mexico.
The storm, which formed last weekend off the coast of Acapulco, briefly made landfall in Mexico. It was expected to continue weakening over the next two days.
The governor of Baja California, Marina del Pilar Ávila Olmeda, suspended classes at schools in the state on Friday because of the storm.
Brandt Maxwell, a meteorologist with the Weather Service in San Diego, said east winds and a “blanket” of moisture would also temporarily exacerbate the prolonged heat that most of the state had been experiencing this week. Rising humidity over the next few days is then expected to mitigate fire risk, he added.
Tens of millions of people in California were under excessive heat warnings on Thursday, according to Weather Service data. Scorching heat had fueled two major wildfires and threatened the state’s power grid. The temperature in Sacramento was 116 degrees on Tuesday, a new daily record for the city.
California has also been grappling with a worsening drought. In May, officials adopted emergency regulations requiring local agencies across the state to cut water use by up to 20 percent. The rules also prohibit the watering of ornamental lawns at businesses or commercial properties.
Though the Atlantic hurricane season, which lasts from June to November, began quietly, two tropical storms grew into hurricanes in recent days, and one swept past Bermuda on Friday, drenching the island in rain. The season has been unusually quiet so far, Mr. Maxwell said, with only five named storms, including two hurricanes.
By comparison, the pace of the Pacific storm season has been more brisk. Eleven named storms have originated there, seven of which became hurricanes, he said.
Researchers have found that hurricanes have grown more intense over the past four decades, fueled by climate change. There were 21 named storms last year, following a record-breaking 30 the year before.
Christine Hauser, McKenna Oxenden and Jill Cowan contributed reporting.