The National Hurricane Center on Wednesday expanded Hurricane Rachel's forecast cone into California, with the system expected to approach the coast as a post-tropical cyclone early Sunday, with a projected landfall area roughly 100 miles south of San Diego and a cone stretching as far north as Orange County, according to USA Today. The New York Post reports the remnants will be ripped apart by a powerful low-pressure system off the coast, sending a slug of tropical moisture north after Southern California baked in triple-digit heat for days. Meteorologist Jason D. Farhang warned residents to "beware of sudden changes in our weather from extreme heat to tropical weather."

No recorded hurricane has made landfall in California while maintaining hurricane strength, and the most recent comparable event was Tropical Storm Hilary in 2023, which crossed into Southern California after landfall in Mexico and produced widespread flooding and emergency rescues in desert communities. Meteorologist Collin Gross noted that Rachel will impact Southern California and Arizona as a post-tropical storm while other systems threaten the Gulf Coast and Mexico, saying "not very often you see several states in the Southwest US in a National Hurricane Center forecast cone." California's coastal waters are generally too cool to sustain a hurricane, forcing an extratropical transition that strips the classic structure but retains moisture, wind and energy.

The stormy weekend follows a historic heat wave: downtown Los Angeles endured four consecutive triple-digit days, the longest such streak ever recorded, while nine daily maximum-temperature records fell across the region, including in LA, Oxnard, Long Beach and Santa Ana, per the New York Post. Meteorologist Ben Brissey said temperatures could plunge 5 to 10 degrees below normal Monday. The rain is a potentially badly needed soaking, but the same tropical moisture can fuel intense downpours in mountains, burn scars and urban areas, with isolated debris flows near recent wildfire burn scars a concern.

Climate scientist Daniel Swain said some models show a strong low-pressure system that could generate onshore winds and more significant coastal flooding. The eastern Pacific remains unusually active: Tropical Depression Twenty-E formed Oct. 7 as the season's 22nd storm and is forecast to become a hurricane by Oct. 9. Meanwhile, average daily sea temperatures in the El Niño 3.4 region hit a record 86 degrees, and Berkeley Earth's Zeke Hausfather noted anomalies now exceed those of any prior El Niño on record, topping 2015 and 1877 marks.