Southern California weather: Heat wave, dangerous rip currents, thunderstorms forecast

LOS ANGELES - Get ready for some hot and humid weather that will bring strong rip currents and elevated surf into the region through Tuesday, according to the National Weather Service.

Heat advisories in effect

What we know:

A ridge of high pressure is causing a very warm to hot air mass to settle across the area and is expected to continue through the middle of the week.

Heat advisories were in effect for most of Los Angeles County through 6 p.m. Tuesday, and in much of Orange County from 10 a.m. Monday to 6 p.m. Tuesday, according to the National Weather Service. 

Highs reached 100 degrees Monday in parts of the Antelope Valley, and were in the high 90s in other valley areas.

Hot and dry conditions will persist away from the immediate coast, with high temperatures of 95 to 107 degrees across the valleys, lower mountains, and deserts, according to the NWS.

Similar hot temperatures may linger into Tuesday, with warmer temperatures making their way to the coast due to a weakening onshore flow.

Additionally, humidity between 10 and 25% will be common over the warmest valleys, lower mountains, and deserts on Monday, then potentially increase by Tuesday or Wednesday due to the change of monsoonal moisture.

The main risks at this time will likely be isolated dry lightning strikes and gusty winds, according to the NWS.

"These isolated dry lightning strikes will bring an increased risk of lightning-induced fires across the region, especially considering the critically dry fuels, the NWS said in its latest forecast.

Dangerous rip currents 

The NWS has issued a hazardous beach statement warning of elevated surf conditions - up to 6 feet - and dangerous rip currents in Los Angeles and Ventura counties.

Rip currents, which flow out toward the ocean, can quickly pull swimmers away from the shore. They typically form at breaks in sandbars and near structures like piers and jetties.

Officials are warning of an increased risk of ocean drownings due to dangerous rip currents expected to peak on Monday. 

There will be an elevated surf of 3 to 6 feet for Los Angeles and Ventura counties, 44 to 7 feet for San Luis Obispo and western Santa Barbara counties and will peak on Monday.

The most dangerous conditions affect south-facing beaches from Point Mugu to Malibu, as well as Port San Luis and Avila beaches, where waves as high as 7 feet are possible.

"There is an increased risk of ocean drowning. Rip currents can pull swimmers and surfers out to sea. Waves can wash people off beaches and rocks, and capsize small boats nearshore," the NWS said.

Those at the beach are urged to swim near a lifeguard. Inexperienced swimmers are strongly advised to stay out of the water.

If you're caught in a rip current, officials advise you to float on your back to conserve energy and swim parallel to the shore until you're out of the current's pull.

The NWS also warned that "rock jetties can be deadly in such conditions, stay off the rocks."

Increased fire risk

There will be widespread elevated fire weather through Friday, with increased risk across the interior mountains and foothills, forecasters said. 

The fire weather conditions will peak Tuesday through Thursday. 

There's a 20% chance of Red Flag Warnings across the mountains/foothills by Monday due to the hot temperatures. Chances for a Red Flag Warning increase for LA and Ventura counties Monday night into Tuesday.

Thunderstorms chances

Additionally, there are chances of monsoonal thunderstorms Monday night through Friday.

The main focus of these storms will be tonight and into Tuesday, particularly over the mountains of eastern Santa Barbara, Ventura, and Los Angeles counties. 

There's a concern that brief, heavy downpours could lead to isolated flash flooding, especially in eastern Los Angeles County on Tuesday.

Here are the projected chances for thunderstorms in the area according to the NWS:

• Monday night into Tuesday morning: 10-20% chance of showers/thunderstorms with limited rainfall across LA and Ventura counties and the coastal waters south of Point Conception.
• Tuesday afternoon into Friday: 15-30% chance for mountains and deserts, highest for LA and Ventura counties; 10-20% chance for coasts and valleys south of Point Conception; Wetter storms likely Wednesday through Friday.

"With wetter storms expected, the main risks during this time frame will be the potential for brief heavy rainfall and flooding threats in the mountains and deserts, along with a continued threat of gusty winds," the NWS said.

Why you should care:

The possibility of thunderstorms raises concerns about flash flooding, particularly in the mountains and deserts. Coastal areas may see their heat advisories end early if clouds and fog persist.

Timeline:

• Monday & Tuesday: The heat continues, but a surge of moisture from the south will bring showers and thunderstorms, especially to the mountains and deserts. Don't be surprised if you see some rain, and watch out for a chance of heavy downpours.
• Wednesday & Thursday: We'll likely see more storms popping up in the afternoons, especially over the Mojave Desert, with the air staying warm and muggy. The clouds could also mess with temperatures, keeping daytime highs a little cooler than expected.
• Friday through the Weekend: A break arrives. A change in the wind pattern will bring in cooler, drier air. This means the humidity will drop, and we can expect a return to more typical coastal weather with fog and clouds returning in the mornings.

What's next:

A slight cooling trend is expected beginning Thursday, with temperatures likely dropping around 5 to 7 degrees the following weekend.

A more stable and drier air mass is anticipated to move in between Friday and Saturday. This shift in flow should end the warm and humid pattern, allowing for the return of low clouds and fog to coastal areas.