Weather Alerts For Diamond Bar, CA

# HEADLINE -------------------- EXTREME HEAT WARNING REMAINS IN EFFECT FROM 10 AM THIS MORNING TO 8 PM PDT FRIDAY HEAT ADVISORY REMAINS IN EFFECT UNTIL 10 AM PDT THIS MORNING # DETAILS -------------------- WHAT For the Heat Advisory, temperatures up to 98. For the Extreme Heat Warning, dangerously hot conditions with temperatures up to 112 expected. WHERE A portion of southwest California. WHEN For the Heat Advisory, until 10 AM PDT this morning. For the Extreme Heat Warning, from 10 AM this morning to 8 PM PDT Friday. IMPACTS Heat related illnesses increase significantly during extreme heat events. ISSUED AT Tuesday, August 25, 2026 at 12:02 AM PDT ISSUED BY National Weather Service Los Angeles/Oxnard CA HEADER URGENT - WEATHER MESSAGE # PRECAUTIONARY/PREPAREDNESS ACTIONS -------------------- Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. # AREAS AFFECTED -------------------- Southeastern Ventura County Valleys, Southern Ventura County Mountains, Western San Fernando Valley, Western Santa Monica Mountains Recreational Area, Calabasas and Agoura Hills, Central Ventura County Valleys, Eastern San Fernando Valley, Eastern San Gabriel Mountains, Eastern Santa Monica Mountains Recreational Area, Interstate 5 Corridor, Lake Casitas, Los Angeles County San Gabriel Valley, Ojai Valley, Santa Barbara County Interior Mountains, Santa Clarita Valley, Santa Susana Mountains, Santa Ynez Mountains Eastern Range, Santa Ynez Mountains Western Range, Western San Gabriel Mountains and Highway 14 Corridor Including the cities of Warm Springs, East Los Angeles, El Monte, Universal City, San Rafael Mountain, Malibu Lake, Tejon Pass, The Angeles Crest Highway, Thousand Oaks, Topanga, Valencia, Westlake Village, Matilija, Piru, Lake Castaic, Mount Baldy, Figueroa Mountain, Newbury Park, Oak View, Sunland, Moorpark, Santa Paula, Ojai, Mount Wilson, Malibu Bowl, Mill Creek, La Canada Flintridge, Big Pine Mountain, Glendale, Meiners Oaks, Oat Mountain, Chatsworth, Wrightwood, Acton, Topatopa Mountains, Montecito Hills, Newhall, Gorman, Pomona, San Gabriel, Woodland Hills, Santa Clarita, Burbank, Fillmore, Pasadena, Simi Valley, Van Nuys, Rose Valley, Pyramid Lake, San Marcos Pass, and Northridge

# HEADLINE -------------------- AIR QUALITY ALERT FOR HARMFUL LEVELS OF OZONE (SMOG) AIR POLLUTION # SUMMARY -------------------- Eastern San Fernando Valley- Including the cities of Burbank, Glendale, and Universal City Eastern San Gabriel Mountains- Interstate 5 Corridor- Los Angeles County Inland Coast including Downtown Los Angeles- Including the cities of Inglewood, Downey, Norwalk, Beverly Hills, and West Hollywood Los Angeles County San Gabriel Valley- Including the cities of Pasadena, San Gabriel, and Pomona Santa Clarita Valley- Including the cities of Santa Clarita, Newhall, and Valencia Santa Susana Mountains- Western San Fernando Valley- Including the cities of Reseda, Woodland Hills, and Northridge Western San Gabriel Mountains and Highway 14 Corridor- 755 AM PDT Tue Aug 25 2026 # DETAILS -------------------- WHAT The South Coast AQMD has issued an air quality alert due to harmful levels of ozone pollution. Visit https://www.aqmd.gov/alertinfo to check current and forecasted air quality levels. WHERE in the the South Coast Air Basin and Coachella Valley. Levels of ozone pollution can vary by time and location depending on emissions and air pollution transport. WHEN from 1 PM Monday to 8 PM Friday. The highest ozone levels typically occur in the afternoon and early-evening hours. IMPACTS Ozone air pollution can cause serious health problems, including trouble breathing, asthma attacks, and lung damage. Everyone can be affected, but sensitive groups such as people with lung disease, older adults, people who are pregnant, children, and those who spend a lot of time outdoors are at greater risk. ISSUED AT Tuesday, August 25, 2026 at 7:55 AM PDT ISSUED BY Relayed by National Weather Service Los Angeles/Oxnard CA HEADER Air Quality Alert Message # PRECAUTIONARY/PREPAREDNESS ACTIONS -------------------- To protect your health, check air quality levels and act as needed: - When Air Quality Index (AQI) levels are "Unhealthy for Sensitive Groups" (orange), sensitive groups as specified above should limit extended or intense outdoor activity. - When AQI is "Unhealthy" (red), everyone may experience health impacts. Sensitive groups should avoid extended time outdoors. - When AQI is "Very Unhealthy" (purple), sensitive groups should avoid all outdoor physical activity. Everyone else should avoid extended or intense outdoor activity. - When AQI is "Hazardous" (maroon), everyone should avoid all outdoor physical activity. - ADDITIONAL DETAILS... To help keep indoor air clean when air quality is poor: - Keep windows and doors closed - Run your air conditioner and/or an air purifier - Do not use whole house fans or swamp coolers that bring in outside air if you have other methods to stay cool - Avoid other sources of pollution such as fireplaces, candles, incense, and grilling To help minimize outdoor ozone air pollution levels: - Limit the use of gasoline powered lawn and garden equipment until evening hours - Try to delay trips to the gas station and the use of household chemicals until the evening