The National Weather Service issued an extreme heat warning effective 10 a.m. Tuesday for much of Los Angeles County, with temperatures expected to reach as high as 110 degrees during the peak of the event on Wednesday and Thursday. The warning remains in place through 8 p.m. Thursday and covers the valleys, mountains, and inland portions of the coastal plain across Southern California’s most densely populated corridors. The NWS is calling this week’s heat episode the most intense of 2026, compounded by monsoonal moisture that is pushing humidity levels well above seasonal norms and limiting overnight cooling.
Key Takeaways
- The NWS extreme heat warning runs from 10 a.m. Tuesday through 8 p.m. Thursday for Los Angeles County valleys, mountains, and inland areas, with Wednesday expected to be the hottest day.
- San Fernando Valley temperatures are forecast to reach 105 on Tuesday, 110 on Wednesday, and 104 on Thursday before roughly 10 degrees of cooling arrives Friday.
- Monsoonal moisture is boosting humidity across the region, with San Diego County recording 65% humidity — 10 to 15 percentage points above normal — raising the risk of heat-related illness.
- Inland Empire and Coachella Valley communities face the most extreme conditions, with some areas forecast to exceed 115 degrees.
- Los Angeles County has activated cooling centers across the region, accessible by calling 211 or visiting ready.lacounty.gov/heat.
How Hot Will It Get Across Southern California?
The NWS Los Angeles office warned that the warming trend building since last week will accelerate sharply Tuesday through Thursday, with Wednesday representing the peak. Inland valleys will bear the heaviest temperatures, with the San Fernando Valley forecast to hit 105 degrees Tuesday, 110 on Wednesday, and 104 on Thursday before onshore flow pushes roughly 10 degrees of relief into the region Friday.
Specific community-level forecasts paint a clear picture of the geographic spread. Santa Clarita is expected to reach 99 degrees, Agoura Hills 97, Pasadena 98, Glendale 94, and Norwalk 93. Downtown Los Angeles, which typically benefits from coastal proximity, is forecast at 89 degrees — warm enough to push above historical averages for mid-July. Riverside, deeper inland, is expected to reach 98 degrees during peak afternoon hours.
A separate heat advisory covers coastal areas of Los Angeles and Orange counties through Thursday evening, where temperatures could still climb into the high 80s and lower 90s. For communities accustomed to sea breezes that moderate afternoon highs, those numbers represent an unusual departure from typical July conditions along the coast.
The most severe readings will hit the Inland Empire and Coachella Valley, where temperatures are forecast to exceed 115 degrees in some desert-adjacent communities. San Bernardino County, Riverside County, and portions of San Diego County’s inland valleys are under their own extreme heat warnings. San Diego County valleys and mountains could reach the mid-90s to 104 degrees during the warning period.
What Makes This Heat Event Different From A Typical Summer Spike?
Two factors distinguish this week’s episode from California’s standard summer heat cycles: humidity and overnight temperatures.
Monsoonal moisture flowing northward from the south is pushing humidity levels across Southern California well above seasonal norms. San Diego County, for instance, recorded roughly 65% humidity on Monday — 10 to 15 percentage points higher than usual for the region. The NWS flagged this moisture as a critical risk multiplier, noting that it limits the body’s ability to cool itself through evaporation and makes outdoor exposure dangerous at lower temperatures than would be the case in the region’s typical dry heat.
The NWS warned of “widespread Major HeatRisk” on Wednesday as the combination of high temperatures and elevated humidity pushes the agency’s heat risk index into its upper tiers. Major HeatRisk indicates conditions where heat-related illness is likely without protective action, and where even healthy, active adults face elevated risk if they work or exercise outdoors.
Overnight temperatures will offer minimal relief. Lows Tuesday night and Wednesday night are expected to remain in the lower 70s across many communities, preventing buildings and pavement from cooling sufficiently before the next day’s heat cycle begins. That cumulative effect is what distinguishes a multi-day heat event from a single hot afternoon. When overnight lows stay above 75 degrees, the human body struggles to recover from daytime heat stress, and the risk of heat exhaustion and heat stroke rises significantly with each successive day.
The monsoonal moisture does carry one upside: a few showers and isolated thunderstorms remain possible Tuesday afternoon and evening in the mountains of Los Angeles County and the Antelope Valley. Those storms will not deliver broad relief, but they could provide brief localized cooling in higher-elevation communities.
What Resources Are Available For Residents?
Los Angeles County has activated its network of public cooling centers across the region, offering free access to air-conditioned spaces for residents who do not have adequate cooling at home. The county’s interactive cooling center map, available at ready.lacounty.gov/heat, shows locations by neighborhood along with hours and accessibility information. Residents can also call 211 for referrals to the nearest available facility.
The City of Los Angeles Emergency Management Department has designated public library branches throughout the city as additional cooling locations during regular business hours. The Los Angeles Department of Transportation is offering air-conditioned rides to many cooling center locations through its DASH bus lines, an important resource for residents who lack transportation.
Los Angeles County Health Officer Muntu Davis underscored the seriousness of the conditions in a public advisory, noting that heat causes more deaths in the United States annually than floods, storms, and lightning combined. Davis identified older adults, young children, outdoor workers, athletes, pregnant individuals, and people with chronic medical conditions as the populations facing the highest risk of heat-related illness during the warning period.
The county’s 211 service line operates 24 hours a day, seven days a week, and connects callers with emergency preparedness information, cooling center locations, and other referral services. The NWS also urged residents to check the agency’s HeatRisk map for real-time conditions in their specific neighborhoods, since temperatures can vary substantially between adjacent communities depending on elevation, distance from the coast, and local terrain.
When Will The Heat Break?
Temperatures are expected to ease gradually heading into the weekend. Onshore flow is forecast to strengthen Friday, bringing increased cloud cover and cooler marine air back into the coastal plain and near-inland areas. The NWS expects conditions to remain above normal through at least Friday, but the dangerous triple-digit temperatures in the valleys and inland areas should moderate by several degrees. For the Inland Empire and desert communities, relief will arrive more slowly. Those areas typically lag coastal cooling patterns by a day or more and could remain above 100 degrees through Saturday before aligning closer to seasonal averages early the following week.
This week’s heat event follows a pattern of recurring heat advisories across Southern California since early July. Climate scientists have pointed to the ongoing strengthening of a Super El Niño cycle as a contributing factor in the elevated baseline temperatures across the American West.
FAQs
How long does the extreme heat warning last? The NWS extreme heat warning is in effect from 10 a.m. Tuesday, July 14, through 8 p.m. Thursday, July 16. Coastal areas are under a separate heat advisory through the same period. Conditions are expected to begin easing Friday.
What temperatures are expected during the peak of the heat event? Wednesday is forecast to be the hottest day, with San Fernando Valley temperatures reaching 110 degrees, Inland Empire areas approaching 100 to 105, and desert communities potentially exceeding 115. Coastal areas could reach the high 80s to low 90s.
Where can residents find cooling centers in Los Angeles County? The county maintains an interactive cooling center map at ready.lacounty.gov/heat with locations, hours, and accessibility details. Residents can also call 211, available 24 hours a day, for referrals to the nearest facility. Public library branches in the City of Los Angeles serve as additional cooling locations.
Why is this heat event considered more dangerous than typical summer heat? Monsoonal moisture is pushing humidity levels significantly above normal, which limits the body’s ability to cool through evaporation. Overnight temperatures in the low 70s will prevent buildings and people from recovering between heat cycles, increasing cumulative health risk with each passing day.
What is the NWS HeatRisk map? The HeatRisk map is a tool from the National Weather Service that shows real-time heat conditions and risk levels by location. Residents can use it to check conditions in their specific neighborhood and determine whether outdoor activity is safe. The map is accessible through the NWS website.
Who is at the highest risk during an extreme heat event? Los Angeles County health officials identify older adults, young children under four years old, outdoor workers, athletes, pregnant individuals, people who live alone, and those with chronic medical conditions as the groups facing the highest risk of heat-related illness during extreme heat events.
