Just about the only thing missing from Southern California’s forecast is snow.

As the state comes off a historic September heat wave, Southern California is bracing for Tropical Storm Kay, a system along the northern coast of Mexico’s Baja California peninsula that will deliver heavy rains, flash flooding, strong winds and muggy conditions through at least Saturday.

Kay was about 200 miles off the coast of San Diego on Friday morning, said Miguel Miller, a meteorologist at the National Weather Service’s San Diego office. The bureau has issued a flurry of advisories about the impending storm.

“We don’t have any snow blizzard warnings, but that’s about all we don’t have,” Miller said.

Record heat is fueling dangerous fires across California, pushing firefighters to the limit and creating ideal conditions for more blazes to spark and spread.

Rain was scattered across San Diego County in the morning, and showers were expected to reach Riverside and Orange counties before midday and San Bernardino by the afternoon, the weather service said. Heavy rains with possible thunderstorms could begin Friday afternoon, starting in San Diego and moving north, and forecasters predicted the rain could last into the evening and Saturday.

Orange County is expected to get about a half-inch of rain, and San Diego County should get about three-quarters on an inch. The mountains in San Diego and Riverside counties are projected to get the most rainfall, with up to 7 inches expected in Riverside County. The low desert areas, including the Coachella Valley, are also vulnerable. A flash flood watch is in effect for all Southern California mountains, valleys and deserts, meteorologists said.

The only areas not under a flash flood watch Friday morning were coastal San Diego County, Orange County and the Santa Ana Mountains, Miller said.

Tropical Storm Kay’s winds are ramping up, with gusts of 90 to 100 mph expected Friday afternoon and evening. A high-wind warning is in effect until midnight throughout the Inland Empire, the mountains of Riverside and San Diego counties and the San Diego coast and valleys. Orange County and the San Bernardino mountains and deserts are under a wind advisory. Even coastal and valley areas could see up to 60 mph winds.

“It will be noticeable,” said Elizabeth Schenk, a National Weather Service meteorologist in San Diego.

The Fairview fire, which has burned 27,463 acres and is only 5% contained, could intensify because of the expected strong winds and storms from Tropical Storm Kay, fire officials said.

The strong gusts could make the already critical fire situation more dire. Near Hemet, the Fairview fire had exploded to more than 27,000 acres Friday — becoming this year’s largest wildfire — with only 5% containment.

The storm is not expected to bring significant rain to Los Angeles County and the surrounding areas, which are likely to stay dry most of Friday, although some rain bursts and thunderstorms could develop by the evening. Meteorologists have issued a flash flood watch for L.A. and Ventura counties, as well as the Antelope Valley. Forecasters are particularly concerned about Catalina Island, which is under a coastal flooding advisory.

Southern California last felt the effects of a tropical storm in 1997, when Tropical Storm Nora caused flooding, power disruptions and traffic crashes, as well as destroyed several homes in Orange County.

Despite the coming rain, excessive heat remained an issue Friday. The temperature in downtown Los Angeles was already at 80 degrees by 9 a.m., said Dave Bruno with the weather service’s Oxnard bureau. Most valley and foothill areas did not drop below 90 overnight.

In this once-in-a-millennium drought, a lawn evangelist like Jim Baird seems as heretical a sight in Los Angeles as an Angels hat at Dodger Stadium.

Storm clouds could prevent record-breaking heat, but temperatures still could reach 100 degrees, even near the coast, forecasters said.

The Inland Empire and Orange County could reach highs from the upper 90s to triple digits, while San Diego County will likely stay in the low 90s.

But a cool-down is coming. “Today will be the last of the extreme days,” Bruno said.

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Alexandra E. Petri covers trends and breaking news for the Los Angeles Times. She previously covered live news at the New York Times. A two-time reporting fellow with the International Women’s Media Foundation, she graduated from Penn State with a degree in journalism and international studies.