Major heat wave set to scorch SoCal as crews continue to battle Flats Fire in Riverside County

PINYON PINES, Calif. (KABC) -- Triple-digit temperatures set to grip the Southland, with the region especially feeling the heat beginning Tuesday, are increasing concerns over the potential for wildfires. Crews are already battling a 400-acre brush fire in the Santa Rosa Mountains.

Firefighters across Southern California are on high alert, with the heat wave expected to bring record-breaking temperatures across part of the area, including in the mountains. Downtown Los Angeles could even reach up to 100 degrees.

Fire danger



The Flats Fire in Pinyon Pines broke out Sunday morning, prompting a mandatory evacuation order for the Pinyon Crest area and the partial closure of State Route 74 Sunday.

RELATED | 400-acre brush fire prompts mandatory evacuation order for Pinyon Crest area
EMBED More News Videos

A wildfire in the Santa Rosa Mountains prompted a mandatory evacuation order for Pinyon Crest and the partial closure of State Route 74 Sunday.



Evacuation warnings were also issued for the nearby communities of Pinyon Pines and Alpine Village. Firefighters say at least two homes were destroyed and three were damaged, in addition to three damaged outbuildings.

By around 5 p.m. Sunday, firefighters said they had stopped the forward rate of spread of the Flats Fire, but weather and terrain issues continue to remain challenges.

Containment was estimated at 10% by 6:30 p.m. Sunday. The cause of the fire remains under investigation.

One firefighter was injured and was transported for medical evaluation.

Los Angeles, Orange and Ventura counties were sharing resources as part of a quick-response force to battle wildfires. The resources include a mobile unit with fire retardant that helicopters can load up and deploy during a fire fight.

Health concerns



The excessive heat also means the risk of heat-related illnesses and a strain on the state's power grid.

The National Weather Service has already issued an excessive heat watch that will be in effect from Tuesday morning through Wednesday evening along the Los Angeles County Coast, including downtown, as well as an excessive heat watch through Friday night across the valleys and mountains.

Forecasters said the extreme heat throughout the region will create "dangerously hot conditions'' with temperatures possibly reaching 113 this week in the Antelope Valley.

"Tuesday through Thursday should be the hottest, when highs between 100 and 110 and minimum humidities between 5 and 15 percent will be common over most mountains and lower mountains,'' according to the NWS. "Monday night through Tuesday night is of particular concern, when north winds increase and enhance the warming and drying over the coasts and nearby valleys.''

For interior valleys, "hot, dry and breezy conditions'' could create critical fire-danger conditions.

"There is still some uncertainty as to when the heat will relax, but there is a potential for little change through next weekend, especially for interior areas,'' according the weather service.

Coastal areas will see relief a little earlier, with onshore flow expected to return by late Wednesday, bringing a return of the marine layer that will bring temperatures down.

The NWS warned that extreme heat will "significantly increase the potential for heat-related illnesses.''

"Be prepared to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and check up on relatives and neighbors,'' according to the NWS. "Young children and pets should never be left unattended in vehicles under any circumstances. This is especially true during warm or hot weather when car interiors can reach lethal temperatures in a matter of minutes.''

RELATED VIDEO | How heat waves form
EMBED More News Videos

It's hotter than normal, and it has been like this for several days. What you're experiencing is a heat wave. How did it form?



The Los Angeles County Health Officer on Friday also issued a Heat Alert starting Monday and ending Wednesday for West San Fernando Valley, East San Fernando Valley, East San Gabriel Valley, Santa Clarita Valley, Antelope Valley and San Gabriel Valley -- reminding everyone in those regions to take precautions to avoid heat-related illness, especially older adults, young children, outdoor workers, athletes, and people with chronic medical conditions.

Public Health issued the following recommendations to stay safe during high temperature days:
-- Drink plenty of water throughout the day;
-- Plan your day to avoid going out during the hottest hours, and wear
sunscreen;
-- Wear lightweight, light-colored clothes, and wear a hat or use an
umbrella;
-- Never leave children or pets in cars and call 911 if you see a
child or pet in a car alone;
-- Beware of heat-related illness, like heat stroke and call 911 if
you or someone you know is experiencing high body temperature, vomiting, and
pale and clammy skin;

-- Check on those at risk, such as those who are sick, older adults,
pregnant women, and children, and those who live alone; and
-- If you are wearing a mask, avoid strenuous workouts wearing face
coverings or masks not intended for athletic purposes.

"While it is very important that everyone take special care of themselves, it is equally important that we reach out and check on others, in particular those who are especially vulnerable to the harmful effects of high temperatures, including children, the elderly, and their pets,'' said Los Angeles County Health Officer Muntu Davis. "High temperatures are not just an inconvenience, they can be dangerous and even deadly.''

County and city partners operate cooling centers during times of high heat. Residents who do not have access to air conditioning are encouraged to take advantage of free cooling centers. To find a location, visit https://ready.lacounty.gov/heat/ or call 211.

Los Angeles County residents and business owners, including people with disabilities and others with access and functional needs can call 2-1-1 for emergency preparedness information and other referral services.

Potential impact on power



The California Independent System Operator, which manages the state's power grid, released a statement saying the agency "could take a number of actions to reduce demand and access additional energy.'' The agency declared a "restricted maintenance operation'' condition that will be in effect from noon to 10 p.m. Tuesday through Friday due to the forecasted high temperatures and demand. The declaration warns that all available resources will be needed to maintain supply, and calls on suppliers to defer scheduled maintenance on generators and transmission lines if possible.

RELATED VIDEO | How wildfire smoke can impact your health
EMBED More News Videos

Smoke from wildfires could cause health problems for some people.



"It is still too early to know the precise impact (the) high temperatures will have on the electricity grid,'' according to Cal-ISO. "But the ISO is closely monitoring conditions and the anticipated increase in demand for electricity and will issue additional public notifications as warranted.''

If necessary, the ISO could issue a Flex Alert, which is a voluntary call for residents to conserve power during peak hours to reduce strain on the grid.



City News Service contributed to this report.
Copyright © 2021 KABC-TV. All Rights Reserved.