SoCal Braces For Tropical Storm, End-Of-Summer Heat Wave

LOS ANGELES, CA — A heat wave with monsoonal characteristics is arriving in the Southland during the last week of summer, followed by a chance of thunderstorms, all of which are elevating concerns for fire danger, weather experts said.

The tropical heat is arriving on the heels of a spell of much cooler weather, which gave Southlanders a brief break from the persistent heat that began in August.

The three-day warming trend is likely to bring humidity and daytime highs in the 80s along the coast and in the high 90s or triple digits further inland, the National Weather Service said.

Weather officials said moisture from Tropical Storm Mario will push temperatures above normal throughout the Southland and could bring Thunderstorms as early as Tuesday afternoon in places like San Diego County.

"Moisture from redeveloping Tropical Storm Mario will become embedded with the monsoonal flow and get transported into southern California between Tuesday and Wednesday," the NWS said in its forecast discussion Monday. "As is frequent with these patterns, there is a great amount of uncertainty how much precipitation and cloud coverage will occur."

By Wednesday and Thursday, many areas in Southern California could see light rain into Friday and the region faces "the threat of brief heavy downpours and flooding," the NWS said.

The heat will begin building in Los Angeles on Monday, with a high of 86 expected before reaching 91 on Wednesday. Meanwhile, along the coast in Carlsbad, temperatures will hit 74 on Monday before rising to 78 on Wednesday with the potential arrival of thunderstorms.

"Remember to remain hydrated with plenty of water and electrolytes, limit time outdoors during peak heating if possible, and never leave children or pets unattended in vehicles," weather officials said.

And while rain is expected mid-to-late week, tropical heat could stick around.

"While temperatures will cool with the increase in moisture and the potential for shower activity, temperatures will likely remain warm and humid into late week," the weather service said.

Here are the highs expected on Wednesday across SoCal:

Carlsbad: 78 degrees

Santee: 90 degrees

Banning: 93 degrees

Temecula: 92 degrees

Palm Desert: 101 degrees (103 degrees on Tuesday)

Laguna Beach: 78 degrees

Mission Viejo: 88 degrees (91 degrees on Tuesday)

Long Beach: 86 degrees

Los Angeles: 91 degrees

Malibu: 80 degrees

Altadena: 95 degrees

The news comes on the heels of a much more intense heat wave last month that brought "highly volatile" triple-digit heat that sparked fires and posed a health hazard to vulnerable communities.

So far, August and September weather forecasts have come in stark contrast to July, which looked a bit more like spring than summer for the month, with gray skies, cool temperatures and a stubborn marine layer hanging on across the region.