Introduction to the Heat Wave
After a relatively mild summer in Southern California, the season’s most intense heat wave is about to arrive. “This is a more impactful, more significant heat wave than really what we’ve seen for the majority of the summer. We’ve had kind of more of a cooler pattern, a lot of marine layer clouds. And so this might catch some people by surprise … but [it] definitely looks pretty warm,” said Lisa Phillips, a meteorologist with the National Weather Service.
Red Flag Warning and Fire Weather Conditions
A Red Flag warning issued by the NWS goes into effect beginning 9 a.m. on Wednesday and continuing to 9 p.m. on Saturday for parts of Los Angeles and Ventura counties, including the 5 Freeway Corridor north of Los Angeles, the Santa Clarita Valley, the San Gabriel Mountains, the Antelope Valley foothills, the 14 Freeway Corridor and the Ventura County Mountains. That means fire-weather conditions are expected to be ripe for explosive fire behavior, per the NWS. Some areas will reach upwards of 100 degrees, as the heat wave develops in Southern California, and forecasters say residents should prepare.
Projected Highs and Cooling Centers
Some projected highs in the region for the heat wave’s peak on Friday include:
- Long Beach: 92
- Pasadena: 101
- Los Angeles: 90
- Santa Ana: 84
- San Clemente: 81
- San Bernardino: 105
- Ontario: 100
- Murrieta: 100
“There’s a lot of places you can go to that are going to have air conditioning, public places like malls, libraries, that kind of thing,” said Phillips. Cooling centers can be found across the region in LA County, Orange County, San Bernardino County, and Riverside County. “Make a plan for if things get too warm where you live and you have to go somewhere else, like know where you’re going to go,” Phillips said.
Expert Tips for Staying Safe
Heat is the deadliest weather-related hazard, killing more than 700 people a year in the U.S., according to the Centers for Disease Control and Prevention, and is preventable. Here are some expert tips:
- Stay hydrated, drink plenty of water and electrolytes
- Stay inside, or in a cool space outside, especially during peak heat times (3-6pm)
- Walk your dog and recreate in the early morning or evening
- Outdoor workers should frequently rest in shaded or air-conditioned areas
- Don’t leave pets and children unattended in vehicles
- Look out for your loved ones and those around you
Recognizing Heat-Related Illnesses
Residents will want to be on the lookout for heat-related illnesses, such as heat exhaustion and the more serious heat stroke. Signs of heat exhaustion include: thirst, heavy sweating, and weakness, according to the CDC. Someone experiencing those symptoms should hydrate and move into a cool area. Though heat exhaustion is important to pay attention to but not deadly, it can turn into a life-threatening heat stroke. Someone suffering from a heat stroke might exhibit a number of the following symptoms: high body temperature, vomiting, nausea, headache, and the person might also stop sweating. They should seek immediate medical attention.
Vulnerable Groups
The following groups should take extra precautions in the heatwave: those 65 years or older, young children, people with chronic health conditions, pregnant people, people experiencing homelessness, those who work outside, and people with disabilities.
Relief from the Heat
As for when residents can expect relief from the heat, “We kind of have to hold out, it’s going to be fairly hot into the weekend,” Phillips said. She’s hopeful that temperatures will begin to gradually cool down early next week.
Conclusion
The upcoming heat wave in Southern California is expected to be the most intense of the season, with temperatures soaring over 100 degrees in some areas. It is crucial for residents to take necessary precautions to stay safe, including staying hydrated, staying indoors during peak heat hours, and being aware of heat-related illnesses. By taking these steps and looking out for vulnerable groups, residents can protect themselves and their loved ones from the dangers of the heat wave.
FAQs
- Q: What is the expected duration of the heat wave?
A: The heat wave is expected to last from Wednesday to Saturday, with temperatures gradually cooling down early next week. - Q: What are the symptoms of heat exhaustion and heat stroke?
A: Signs of heat exhaustion include thirst, heavy sweating, and weakness. Signs of heat stroke include high body temperature, vomiting, nausea, headache, and the person might also stop sweating. - Q: Where can I find cooling centers in my area?
A: Cooling centers can be found across the region in LA County, Orange County, San Bernardino County, and Riverside County. You can search online or check with local authorities for specific locations. - Q: What groups are most vulnerable to heat-related illnesses?
A: The following groups should take extra precautions in the heatwave: those 65 years or older, young children, people with chronic health conditions, pregnant people, people experiencing homelessness, those who work outside, and people with disabilities.Originally Published: August 18, 2025 at 5:51 PM PDT
