"Virtually impossible" without climate change, this March heat wave has shattered over 1,100 daily records across the United States.
A severe and widespread heat wave has impacted large portions of the western United States, breaking hundreds of temperature records for the month of March. The event, which has brought summer-like temperatures weeks ahead of schedule, has prompted heat warnings and advisories across multiple states.
Affected Regions and Temperature Ranges
California
- Northern California, including the Sacramento Valley and Shasta County, experienced highs up to 110°F.
- Palm Springs reached 107°F on Thursday, surpassing its previous March record of 105°F set the day prior.
- Indio recorded 108°F on Thursday, establishing a new March high.
- North Shore tied the previous US March record of 108°F on Wednesday.
- Woodland Hills recorded 102°F on Thursday, exceeding its 1997 record of 96°F.
- Lancaster reached 93°F on Thursday, surpassing its 2004 record of 87°F.
- Hollywood Burbank Airport reached 92°F on Monday, breaking its 2004 daily record of 91°F.
- Daily records were set in Riverside (101°F), Anaheim (95°F), Sacramento (88°F), San Francisco (85°F), and San Diego (85°F).
Arizona
- Martinez Lake recorded 110°F on Thursday, establishing a new US record for the highest March temperature.
- Phoenix experienced its earliest triple-digit day on record (March 19) at 102°F, followed by 104°F on Thursday.
- Tucson reached 98°F on Friday, with forecasts calling for 100°F.
- Hiking trails around Phoenix were closed due to heat illness risks.
Nevada
- Las Vegas set a new March record of 95°F on Thursday, with potential to reach 100°F on Friday.
Oregon and Washington
- Portland metro area and Vancouver experienced highs of 95–100°F.
- The Columbia River Gorge was also affected.
Other Western States
- Boise, Idaho, reached 80°F on Wednesday, marking its earliest date for such a temperature since records began in 1875.
- Parts of Oregon, Idaho, and Wyoming experienced unseasonably warm conditions.
- Colorado forecasters predicted highs in the 80s for Denver, Fort Collins, and Boulder.
Timeline of the Event
Monday, March 17
- A strong ridge of high pressure began developing over the region.
- Hollywood Burbank Airport recorded 92°F; Pierce College in Woodland Hills reached 97°F.
- Heat advisories were issued across Southern California.
Tuesday, March 18 through Friday, March 21
- Peak heat conditions were observed across the Southwest.
- Multiple cities set daily and monthly temperature records.
- Extreme heat warnings were active for much of Los Angeles County and portions of Arizona.
- Temperatures in Southern California reached the 80s and 90s along the coast and exceeded 100°F inland.
Saturday, March 22
- Southern California temperatures began moderating, with coastal areas reaching upper 70s and low 80s.
- Inland and valley regions experienced low 90s.
- Further cooling was forecast for Sunday.
National Weather Service Advisories
Risk Level: The NWS classified the event as a "Major Heat Risk" for affected areas.
The National Weather Service issued heat advisories and extreme heat warnings across affected areas. California and Arizona:
- An extreme heat warning was active from Tuesday morning through Friday evening for much of Los Angeles County.
- Expected temperatures ranged from 96°F to 104°F.
- An extreme heat warning was in effect for Phoenix through Sunday.
Overnight lows were projected to remain in the 70s in California and low-to-mid 60s in Oregon and Washington. Some foothill areas may not drop below 80°F at night, which exceeds normal March highs for those regions.
Record Statistics
According to the National Weather Service:
- Between March 15 and March 26, more than 100 monthly records and 700 daily records were broken or tied across the country.
- Since March 1, over 1,100 daily records have been broken or tied nationwide.
- Many cities experienced their hottest March day in nearly 40 years.
- The average first 105°F day typically occurs on May 22.
Scientific Analysis
World Weather Attribution, an international consortium of climate researchers, conducted a rapid analysis of the heat wave. Their findings, based on forecasts for a five-day period from March 18-22, concluded that the event would have been "virtually impossible" without the effects of climate change.
Global heating has quadrupled the likelihood of such a heatwave over the past decade.
According to the analysis:
- Even in 2016, the current heatwave would have been approximately 1.4°F (0.8°C) cooler.
- The climate crisis, primarily caused by the burning of fossil fuels, contributed to these conditions.
Fire Weather Warnings
Red flag warnings were issued by the National Weather Service for over 47 million Americans, spanning from the Great Plains to the Southeast.
- Plains and Southeast: Wind gusts of 30 to 60 mph were projected for Saturday. Combined with low humidity and dry fuels, these conditions created an increased risk of rapid wildfire growth.
- Colorado: The NWS issued warnings regarding increased wildfire risks due to extreme heat, gusty winds, and low humidity.
- Nebraska: The Cottonwood and Morrill fires burned over 1,200 square miles (3,118 square kilometers) before being largely contained. Evacuation orders were lifted for affected areas.
Temperature Projections
Southwest
- Temperatures were expected to remain 20 to 30 degrees Fahrenheit above normal for March through the remainder of the week. A slight decrease was expected on Sunday.
Midwest
- Nebraska was forecast to see temperatures above 90°F, with a subsequent drop to the 50s and 60s on Sunday. Portions of Texas reached 90°F or higher on Saturday.
Northeast
- A cooldown moved across the Midwest and Northeast following unseasonably warm spring days. Cities like Chicago and New York City were expected to be noticeably cooler on Saturday.
Long-Term Outlook
The National Weather Service indicated that April, May, and June are likely to be hotter than normal across most of the US, with the exception of the Northeast and Great Lakes regions. Arizona, Nevada, Utah, and New Mexico are predicted to have a hotter spring than typical.
Public Health & Safety
Cold-Water Shock Risk
Officials warned of cold-water shock in rivers and lakes fed by snowmelt. Sudden immersion can trigger rapid breathing and loss of muscle control, potentially leading to drowning even in strong swimmers.
Economic Impact
Multiple California and Tahoe-area ski resorts were forced to close or reduce operations due to rapid snowmelt and high temperatures.
Public Health Recommendations
The California Department of Public Health identified the following groups as being at greatest risk: unhoused individuals, outdoor workers, older adults, infants, children, pregnant people, and those with chronic health conditions or disabilities.
Cooling centers were made available at public libraries and community centers across Los Angeles County from 11 a.m. to 7 p.m.
The NWS advised residents to:
- Stay in air-conditioned or cool indoor spaces
- Drink fluids, avoid alcohol and excess caffeine
- Wear lightweight and loose clothing
- Keep windows and doors closed during the day and open at night
- Avoid strenuous outdoor activity between 10 a.m. and 5 p.m.
- Check on vulnerable neighbors and loved ones
- Recognize symptoms of heat-related illness