Wed Sep 17 22:40:00 UTC 2025: ## Southland Braces for Muggy Heat Wave, Monsoon Rain, and Flash Flood Risk

**Los Angeles, CA -** Southern California is facing a week of sweltering humidity and the potential for monsoonal moisture, bringing with it the risk of thunderstorms, flash flooding, and even debris flows in burn scar areas.

The National Weather Service (NWS) issued a statement Tuesday night warning of the incoming weather system, remnants of Tropical Storm Mario, which will bring higher-than-normal humidity levels through Friday. “It will be warm and muggy through Friday as remnants of tropical storm Mario move into the area. Temperatures will cool through the period but humidities will be much higher than normal,” the NWS said.

Rain and thunderstorm chances are expected to begin Wednesday night and continue into at least early Friday. Rainfall amounts are predicted to be highly variable across the region, ranging from a tenth of an inch to as much as 1-2 inches in some areas.

While the initial threat Wednesday night into early Thursday is dry lightning and localized strong winds, the NWS is urging residents to be prepared for flash flooding as more moisture arrives on Thursday, particularly near recent burn scars where debris flows are possible.

Daytime temperatures are expected to drop slightly, about 5 degrees from Tuesday, but overnight lows will be significantly warmer due to the increased humidity, remaining in the upper 60s and low 70s in inland areas.

The City of Los Angeles is taking the impending weather seriously. Mayor Karen Bass’ office announced it is actively monitoring the forecast and coordinating with key departments including the Emergency Management Department, fire and police departments, Recreation and Parks, and the Department of Water and Power to ensure a coordinated response to any potential emergencies.

The city has also opened hundreds of cooling centers at recreation and parks facilities and local library branches for residents seeking relief from the heat. Information on locations and hours of operation can be found at laparks.org/reccenter or lapl.org/branches. Residents can also call 311 for more information.

Residents are advised to stay informed of the latest weather updates and to take necessary precautions to stay safe during the heat and potential flooding. This includes staying hydrated, seeking shelter from the sun, avoiding areas prone to flooding, and being prepared for potential power outages.

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