# US heat dome causes record temps, rescues, and farm impacts > Live situation record from CLSTR: https://clstr.news/situations/southern-california-heat-wave-june-2026 > Updated: 2026-08-09T07:04:00.000Z. Sources: 123. Developments: 20. The slow-moving high-pressure heat dome over the western United States has maintained record-breaking temperatures. By early August, the National Weather Service issued Extreme Heat Warnings for desert zones including the Indian Wells Valley, Mojave, Coachella, and the Phoenix metropolitan area, with temperatures exceeding 110 °F. In Southern California, the heat wave drove a record 1,950 ocean rescues in Los Angeles County on August 5, as high temperatures and six-foot swells created dangerous rip currents. Simultaneously, health officials issued water-quality warnings for several piers, including Venice and Santa Monica, after bacterial levels exceeded state standards. Agricultural impacts have become significant. In the Imperial and Central Valleys, triple-digit heat has prompted warnings for outdoor workers. In Tulare County, dairy operators are implementing cooling measures to mitigate cattle mortality. By mid-August, the heat dome's influence expanded, with meteorologists estimating 70–80 million people were under extreme-heat warnings. This has forced shifts in daily routines for construction and agriculture, alongside spikes in energy demand. While some regions, such as the Midwest, faced concurrent threats of severe storms and high heat indices, the Desert Southwest experienced a mix of extreme heat and isolated thunderstorms. In Imperial County, wind-blown dust triggered air quality alerts. A cold front is expected to bring cooler, milder temperatures and lower humidity by late August. ## Claims - The National Weather Service issued an Extreme Heat Warning for the Inland Empire (San Bernardino and Riverside counties) from July 29 10 a.m. to August 2 8 p.m., forecasting temperatures up to 110‑12 (corroborated by 4 sources) - Extreme heat warnings were issued for parts of the Southwest United States with forecast temperatures up to 120 °F. (corroborated by 4 sources) - A heat dome is covering much of the western United States, causing record high temperatures. (corroborated by 4 sources) - Residents are advised to stay in air‑conditioned spaces, drink water regularly, avoid the hottest part of the day, check on vulnerable neighbors, and use public cooling shelters. (corroborated by 3 sources) - Heat stroke is a medical emergency; call 911 if body temperature exceeds 103 °F, or if loss of consciousness, confusion, or other severe symptoms occur. (corroborated by 3 sources) - The National Weather Service issued an Extreme Heat Warning for the Inland Empire (San Bernardino and Riverside counties) from July 29 10 a.m. to August 2 8 p.m. with temperatures forecast at 110‑120 (corroborated by 3 sources) - Death Valley is forecast to hit about 52.2 °C (126 °F). (corroborated by 3 sources) - Around 40 million people are under heat alerts. (corroborated by 3 sources) - At least 12 states will see record high temperatures during the weekend. (corroborated by 3 sources) - More than 12 million people face extreme heat risk level 4, and another 12 million face level 3. (corroborated by 3 sources) - Climate‑change research indicates such intense, slow‑moving heat domes are becoming more likely. (corroborated by 3 sources) - More than 40 million people are under heat alerts in the United States. (corroborated by 3 sources) - The National Weather Service issued an extreme heat warning for the Inland Empire of Southern California from July 29 to August 2. (corroborated by 2 sources) - Forecasted afternoon temperatures during the warning are expected to reach between 110 °F and 120 °F. (corroborated by 2 sources) - The heat warning also covers San Diego County and regions in Arizona (Parker Valley, Yuma) and California valleys (Chuckwalla, Imperial, Palo Verde). (corroborated by 2 sources) - Heat‑related illnesses increase sharply during multi‑day extreme heat events. (corroborated by 2 sources) - The National Weather Service issued an extreme heat warning for the Inland Empire from July 29 to August 2. (corroborated by 2 sources) - Daytime temperatures in the warned area are expected to reach 110‑120°F. (corroborated by 2 sources) - Older adults, outdoor workers and people on certain prescriptions are at higher risk of heat illness during prolonged extreme heat events. (corroborated by 2 sources) - The Occupational Safety and Health Administration recommends frequent rest breaks in shaded or air‑conditioned areas for outdoor workers during extreme heat. (corroborated by 2 sources) - OSHA recommends that employers schedule frequent rest breaks in shaded or air‑conditioned environments during extreme heat. (corroborated by 2 sources) - Public cooling shelters are available in some affected areas, and residents without air conditioning can call 211 for assistance. (corroborated by 2 sources) - San Diego County provides 80 air‑conditioned Cool Zones in its 33 public libraries for residents without adequate cooling. (corroborated by 2 sources) - The Occupational Safety and Health Administration advises employers to schedule frequent rest breaks in shaded or air‑conditioned areas for outdoor workers during extreme heat (corroborated by 2 sources) - Older adults, outdoor workers and people taking certain medications (diuretics, ACE inhibitors, ARBs, antipsychotics) have higher risk of heat‑related illness during prolonged extreme heat events (corroborated by 2 sources) - Heat stroke is a medical emergency; callers should dial 911 if symptoms such as body temperature above 103 °F, confusion or loss of consciousness occur (corroborated by 2 sources) - Temperatures in Death Valley are forecast to reach about 52.2 °C (119 °F). (corroborated by 2 sources) - The National Weather Service issued extreme‑heat warnings for 19 U.S. states. (corroborated by 2 sources) - Certain prescription medications (diuretics, ACE inhibitors, ARBs, antipsychotics, anticholinergics, stimulants) increase the risk of heat‑related illness. (single source) - The warning includes valley floor cities such as Riverside, San Bernardino, Ontario, Corona, Moreno Valley, Fontana and Rancho Cucamonga, with a separate heat advisory for higher elevations. (single source) - Medications like diuretics, ACE inhibitors, angiotensin receptor blockers, antipsychotics, anticholinergics and stimulants increase heat‑related illness risk. (single source) - San Diego County offers 80 air‑conditioned Cool Zones in 33 public libraries for residents to escape extreme heat. (single source) - OSHA recommends frequent rest breaks in shaded or air‑conditioned areas for outdoor workers during extreme heat. (single source) - Heat stroke can be fatal and requires immediate emergency response, including calling 911. (single source) - The warning covers valley‑floor cities including Riverside, San Bernardino, Ontario, Corona, Moreno Valley, Fontana and Rancho Cucamonga. (single source) - Older adults, outdoor workers and people taking diuretics, ACE inhibitors or antipsychotics have higher risk of heat‑related illness during prolonged extreme heat (single source) - San Diego County is in its fourth consecutive week of extreme heat, with health advisories urging continuous hydration, avoidance of peak heat hours, and use of county ‘Cool Zones’ such as air‑‑ (single source) - An Extreme Heat Warning also covers Arizona’s Parker Valley and Yuma, and California’s Chuckwalla, Imperial and Palo Verde valleys until August 2, with temperatures expected between 110 °F and 120 °F. (single source) - Heat‑related illnesses such as heat cramps, heat exhaustion and heat stroke are expected to rise during the warning period. (single source) - Public cooling shelters are available in some affected areas during the extreme heat warning. (single source) - Temperatures in Southern California desert communities are expected to climb between 115 and 120 °F. (single source) - Extreme heat was the leading weather‑related cause of death in the United States in 2023, with over 2,300 heat‑related deaths. (single source) - Heat advisory for southwest California coast predicts temperatures of 85‑100 °F from July 29 to August 2. (single source) - An Extreme Heat Warning for Arizona forecasts afternoon temperatures of 107 to 120 °F. (single source) - A heat advisory for southwest California coastal areas forecasts temperatures of 85‑100 °F from July 29 to August 2 (single source) - Extreme Heat Warning also covers portions of northwest Arizona, southeast California and southern Nevada with highs of 110‑120 °F (single source) - A separate Heat Advisory covers San Bernardino County mountains with highs of 90‑100 °F. (single source) - The National Weather Service issued heat alerts for 19 U.S. states. (single source) - Temperatures could exceed 49 °C (120 °F) due to the heat dome. (single source) - Temperatures could reach up to 50 °C (122 °F) in California. (single source) - The Imperial Irrigation District extended its voluntary energy‑conservation alert through Sunday night because of high electricity demand from triple‑digit temperatures (single source) - Arizona Public Service and Salt River Project each set new demand peaks of 9,053 MW and 9,072 MW on a 117 °F day, while the grid remained reliable (single source) - Los Angeles is experiencing unusually high humidity caused by a Pacific marine heat wave, making temperatures feel four to eight degrees hotter than the actual reading (single source) - Imperial Irrigation District extended its voluntary energy‑conservation alert through Sunday night because of triple‑digit temperatures. (single source) - Arizona Public Service and Salt River Project set demand peaks of 9,053 MW and 9,072 MW on a 117 °F day, and the grid remained reliable. (single source) - Palm Springs will host its first Extreme Heat Summit on Sept 18 at the Palm Springs Convention Center. (single source) - San Diego County closed the El Capitan, Hellhole Canyon and Mt. Gower parks through August because of extreme heat. (single source) - A heat wave expected to bring triple‑digit temperatures (up to 105‑106 °F) to Folsom and the Sacramento region from Friday through early next week. (single source) - More than 40 million Americans were placed under heat‑related alerts. (single source) - The Imperial Irrigation District extended a voluntary energy‑conservation alert through Sunday night because of high electricity demand from triple‑digit temperatures. (single source) - Palm Springs will host its first Extreme Heat Summit on 18 September at the Palm Springs Convention Center. (single source) - San Diego County provides 80 air‑conditioned Cool Zones in its 33 public libraries. (single source) - OSHA recommends frequent rest breaks for outdoor workers during extreme heat. (single source) - Temperatures in Death Valley reached 119 °F during the heat wave. (single source) - Extreme heat reduced the output of a Tesla Powerwall installed outdoors in Arizona. (single source) - Imperial Irrigation District extended a voluntary energy‑conservation alert through Sunday night because of high electricity demand. (single source) - San Diego County closed three parks for August due to extreme heat. (single source) - Palm Springs will host its first Extreme Heat Summit on 18 September. (single source) - An Arizona homeowner reported that a Tesla Powerwall installed outdoors reduced output during extreme heat. (single source) - The National Weather Service issued an Extreme Heat Warning for Southern California desert areas through Wednesday night with temperatures up to 112 °F. (single source) - The warning covers Indian Wells Valley, the Mojave Desert and communities including Ridgecrest, California City and Edwards Air Force Base. (single source) - Kern County recorded a heat‑related death of a 43‑year‑old man in May. (single source) - Cal/OSHA warned employers that violations of heat‑illness protection rules can incur civil penalties up to $162,851 per violation. (single source) - Temperatures in the Coachella Valley and other desert locations are expected to reach 110‑113 °F this week. (single source) - Inland Bay Area cities could see highs in the upper 90s, possibly reaching triple‑digit temperatures, while coastal areas stay cooler. (single source) - An Extreme Heat Warning for Phoenix and southern Arizona remains in effect through the weekend with temperatures above 110 °F. (single source) - Heat advisories and extreme‑heat watches were issued for the Greater Reno‑Carson City‑Minden area with highs of 98‑102 °F. (single source) - Cal/OSHA issued an advisory to employers as inland valley temperatures are forecast at 105‑110 °F, urging compliance with heat‑illness prevention standards. (single source) - The National Weather Service issued an Extreme Heat Warning for Imperial County, California, with afternoon temperatures of 104‑117 °F. (single source) ## Timeline ### 2026-08-09: Extreme heat and severe storms impact multiple US regions Extreme heat and severe weather alerts are impacting the US, with high heat indices in Illinois and Missouri, and storm and flood risks in California, including hiking trail closures in San Diego. 8 sources. https://clstr.news/cluster/extreme-heat-warnings-issued-for-parts-of-california-and-arizona ### 2026-08-06: United States heat dome forces daily life changes for millions A heat dome over the US has driven temperatures to 48 °C, affecting 70‑80 million people, prompting health warnings, shifts in work schedules, higher energy use and new cooling‑center initiatives. 2 sources. https://clstr.news/cluster/united-states-heat-dome-forces-daily-life-changes-for-millions ### 2026-08-05: California, Arizona hit triple‑digit heat; farms and officials warn Triple‑digit heat across California and Arizona triggers warnings; Tulare dairy farms adopt cooling measures to protect cattle and advise public safety steps. 6 sources. https://clstr.news/cluster/california-arizona-hit-tripledigit-heat-farms-and-officials-warn ### 2026-08-05: Los Angeles County beaches see rescues, issue water warnings in heat wave Heat wave drives record 1,950 rescues on Los Angeles County beaches while officials issue water‑quality warnings at several piers due to high bacteria levels. 4 sources. https://clstr.news/cluster/los-angeles-county-beaches-see-rescues-issue-water-warnings-in-heat-wave ### 2026-08-02: National Weather Service Issues Extreme Heat Warnings Across Western U.S NWS issued extreme heat warnings for California deserts, Coachella Valley, Phoenix, Reno area and Imperial County, with temps up to 117 °F; a Kern County heat death was recorded and Cal/OSHA warned of up to $‑$ 10 sources. https://clstr.news/cluster/california-heat-wave-triggers-extreme-warnings ### 2026-07-30: Southern California Heat Wave Sparks Ozone Advisory and Fire Threats A Southern California heat wave triggers an ozone advisory, a brush fire on the 5 Freeway, and heightened fire‑weather risk, while a strong El Niño may prolong heat and affect winter precipitation in Santa Barb 4 sources. https://clstr.news/cluster/goleta-coffee-community-event-and-santa-barbara-downtown-activities-in-august ### 2026-07-29: Western U.S. Heat Dome Triggers Record Temperatures and Alerts A western U.S. heat dome pushes record temperatures—up to 119 °F in Death Valley—affects 40 million people, spikes power demand, triggers alerts, park closures and a new heat‑resilience summit. 27 sources. https://clstr.news/cluster/extreme-heat-alerts-issued-for-southern-california-and-arizona ### 2026-07-29: California Central Valley faces record heat, prompting paramedic alerts and nonprofit cooling stations Extreme heat in California's Central Valley drives paramedic warnings in Fresno and leads Imperial County nonprofits to set up hydration stations for vulnerable residents. 5 sources. https://clstr.news/cluster/california-central-valley-faces-record-heat-prompting-paramedic-alerts-and-nonprofit-cooling-station ### 2026-07-18: Southern California Endures Record Heat Wave Amid Remnants of Tropical Storm Elida Southern California faces a record heat wave with temps up to 108 °F, heat advisories, and fire‑risk warnings, intensified by Tropical Storm Elida remnants. 13 sources. https://clstr.news/cluster/us-service-members-killed-in-iranian-strikes-as-spain-wins-world-cup ### 2026-07-15: US Southwest Heat Dome Drives Record Temperatures Across Multiple States A heat dome over the Rockies set record highs in Montana, Wyoming, Utah and other western states in July 2026, spiking heat‑related emergencies and prompting forecasts of further extreme temperatures eastward. 8 sources. https://clstr.news/cluster/california-records-hottest-june-since-1895-data-show ### 2026-07-15: Los Angeles County Issues Bacteria Warnings for Multiple Southern California Beaches LA County health officials warned that bacterial levels at several Southern California beaches exceed state standards, urging the public to avoid swimming amid a regional heatwave. 2 sources. https://clstr.news/cluster/los-angeles-county-issues-bacteria-warnings-for-multiple-southern-california-beaches ### 2026-07-14: Southern California Heat Wave Triggers Wildfire Warnings, Power Shutoffs and Cooling Centers A California heat wave with triple‑digit temps has prompted extreme‑heat warnings, Red Flag fire alerts, power‑shutoff plans in Santa Barbara, cooling centers statewide, and altered work schedules for farm‑work 11 sources. https://clstr.news/cluster/southern-california-heat-wave-drives-beach-visits-cooling-centers-and-extreme-warnings ### 2026-07-14: PG&E warns of power shutoffs in Bay Area, Central Coast amid heat and wind PG&E warns of PSPS power outages for thousands of Bay Area and Central Coast customers on July 15‑16 due to heat, wind and wildfire risk, affecting multiple counties and setting up resource centers. 11 sources. https://clstr.news/cluster/california-fire-risk-spikes-as-gusty-winds-spark-power-shutoff-alerts ### 2026-07-14: U.S. record‑breaking heat wave sweeps West to East A heat dome drives a record‑breaking U.S. heat wave, shattering western temperature records and putting nearly 100 million people on heat alert as it moves east, with climate change and El Niño cited as amplif​ 20 sources. https://clstr.news/cluster/us-heat-dome-hits-nearly-100-million-shattering-records-from-west-to-east ### 2026-07-12: Southern California Heat Wave and Monsoon Threat Heat warnings across Southern California call for precautions as temperatures hit 90‑110 °F, fire risk rises, and monsoonal moisture brings flood and thunderstorm threats. 5 sources. https://clstr.news/cluster/california-heat-advisory-raises-temperatures-and-fire-risk-across-bay-area-and-riverside-county ### 2026-07-12: U.S. heat wave triggers record temperatures and widespread alerts A U.S. heat dome drives record temperatures, heat‑index up to 115 °F, affects 40 M people, sparks warnings in 23 states, worsens wildfire risk and threatens vulnerable populations. 30 sources. https://clstr.news/cluster/southern-california-heat-wave-triggers-extreme-heat-watches-in-riverside-and-san-bernardino-counties ### 2026-07-08: California heat wave spurs air pollution alerts and beach water warnings A California heat wave drives ozone spikes and dust in the Central Valley and prompts Los Angeles County to issue beach water warnings for elevated bacteria at several sites. 2 sources. https://clstr.news/cluster/california-heat-wave-spurs-air-pollution-alerts-and-beach-water-warnings ### 2026-07-03: California heat forecast raises fire and health risks for July 4 California’s July 4 forecast shows near‑normal coastal temps, hotter inland heat up to 115 °F, and increased fire and health risks. 2 sources. https://clstr.news/cluster/california-heat-forecast-raises-fire-and-health-risks-for-july-4 ### 2026-06-21: Southern California heat spell brings soaring temperatures and high humidity Southern California faces a heat wave with mid‑to‑upper 90s °F temperatures, high humidity, and a heat advisory through Thursday, urging residents to stay cool and hydrated. 2 sources. https://clstr.news/cluster/southern-california-heat-spell-brings-soaring-temperatures-and-high-humidity ### 2026-06-20: Southern California heat forecast peaks at 110°F under high‑pressure ridge Southern California will experience clear skies and extreme heat through late June 2026, with highs up to 110°F inland and minimal rain, while occasional early‑morning marine clouds affect coastal valleys. 2 sources. https://clstr.news/cluster/southern-california-heat-forecast-peaks-at-110f-under-highpressure-ridge --- Cite as: US heat dome causes record temps, rescues, and farm impacts. CLSTR, https://clstr.news/situations/southern-california-heat-wave-june-2026