Southwest Heat Wave Breaks U.S. March Temperature Record With 110°F Near Martinez Lake, Arizona
A sweeping Southwest heat wave set a new U.S. March temperature record when the National Weather Service reported 110°F (43.3°C) near Martinez Lake in the Yuma Desert, surpassing the previous 108°F March high set in 1954 and tied this week in North Shore, California. The extreme warmth—running about 20–30°F above normal—produced numerous city-level March records or near-records (including multiple 108°F readings in California deserts, Phoenix’s earliest triple‑digit readings, and new highs in Las Vegas and Los Angeles), prompted heat alerts for more than 41 million people and heightened warnings about heat‑illness risk.
📌 Key Facts
- The National Weather Service reported 110°F (43.3°C) recorded near Martinez Lake, Arizona (in the Yuma Desert), the highest March temperature ever recorded in the United States.
- The previous U.S. March record of 108°F (set in Rio Grande City, Texas, in 1954) was tied March 18 in North Shore, California; additional California desert locations including Cathedral City and Thermal also hit 108°F, and Thermal was forecast to reach 110°F.
- Phoenix recorded unusually early triple‑digit heat — reaching 101°F on March 18 and then 105°F on Thursday — setting new March records; extreme heat prompted closures of Phoenix hiking trails due to heat‑illness risk.
- Las Vegas set a new March high (reported up to 99°F), breaking its prior March record of 93°F from 2022.
- Downtown Los Angeles reached 94°F, surpassing its previous daily record of 87°F from 1997, and Palm Springs hit 104°F, tying its hottest March day on record from 1966.
- The National Weather Service said many locations across the Southwest were running 20–30°F above normal for March; NWS meteorologist Bryan Lewis described the event as “one of the most significant March heat waves in recorded history,” with numerous records broken in a short span.
- More than 41 million people were under heat alerts through Sunday, and forecasters warned temperatures could stay unusually high into the weekend with many cities possibly seeing their earliest 100°F days on record.
📊 Relevant Data
Climate change has exacerbated the intensity of the March 2026 heat wave in the Southwest US, making such extreme events far more likely due to human-caused factors.
Extraordinary, climate change-fueled heat wave envelops the West — CNN
Agricultural workers in the US are 35 times more likely to die from heat-related stress than workers in other occupations, with many working in extreme heat conditions in areas like the Southwest.
As farmworkers face longer, hotter harvest seasons, their risk of heat-related illness grows — WHYY
Approximately 73% of US agricultural workers are Hispanic, compared to Hispanics making up about 19% of the overall US population, increasing their exposure to heat risks in states like Arizona.
Potential Implications of Immigration Restrictions on the U.S. Agricultural Workforce — KFF
The 1965 Immigration and Nationality Act repealed national-origins quotas, contributing to increased immigration from Latin America and shaping the demographics of agricultural workers in the US, with immigrants comprising nearly three-quarters of farm workers.
Immigration issues have an importance to Arizona farmers, in terms of workforce — NPR
In Maricopa County, Arizona, Hispanic/Latinx populations are more exposed to extreme heat compared to other groups, due to socio-demographic factors and urban heat patterns.
Exploring air temperature variability and socio-demographic disparities in Maricopa County, Arizona — ScienceDirect
📰 Source Timeline (4)
Follow how coverage of this story developed over time
- National Weather Service reports 110°F (43.3°C) recorded near Martinez Lake, Arizona, in the Yuma Desert, now the highest March temperature ever recorded in the United States.
- The previous 108°F March record, set in Rio Grande City, Texas in 1954 and tied Wednesday at North Shore, California, was surpassed on Thursday.
- Additional California desert locations, including Cathedral City and Thermal, hit 108°F Thursday, with Thermal forecast to reach 110°F on Friday.
- Phoenix reached 105°F Thursday, breaking the 102°F March record set the day before and marking its earliest triple‑digit day on record; Las Vegas hit 95°F, also a March record.
- Phoenix hiking trails were closed Thursday because of heat‑illness risk as temperatures across the Southwest stayed 20–30°F above normal for March.
- Confirms the record-tying 108°F reading occurred in North Shore, California, explicitly naming the community.
- Notes that more than 41 million people remain under heat alerts through Sunday, according to CBS News meteorologist Nikki Nolan.
- Provides additional city-level records: Las Vegas hit 99°F (breaking its prior March record of 93°F), downtown Los Angeles reached 94°F (beating a 1997 daily record of 87°F), and Palm Springs hit 104°F (tying its March record from 1966).
- Reports Phoenix’s earliest-ever triple-digit reading in March at 101°F on Wednesday, breaking the previous March 26, 1988 record and marking only the second March 100°F day on record there.
- Quotes NWS meteorologist Bryan Lewis calling this "one of the most significant March heat waves in recorded history" and emphasizing how many daily records have already been broken.
- Projects that the aptly named Thermal, California, was forecast to reach 110°F on Friday and that many other cities may see their earliest 100°F day on record, with temperatures staying 20–30°F above normal into the weekend.
- North Shore, California, hit 108°F on Wednesday, March 18, 2026, tying the highest March temperature ever recorded in the United States, previously set in Rio Grande City, Texas, in 1954.
- The nearby community of Thermal, California, is forecast to reach 110°F on Friday, which would break the existing March record if realized.
- Phoenix reached 101°F on March 18, its earliest 100-degree day on record and only the second time it has hit triple digits in March (the previous was 100°F on March 26, 1988).
- Las Vegas reached 99°F, setting a new all‑time March record and breaking its prior March high of 93°F from 2022.
- Downtown Los Angeles hit 94°F, surpassing its previous daily record of 87°F set in 1997, while Palm Springs reached 104°F, tying its hottest March day on record from 1966.
- NWS meteorologist Bryan Lewis said this is one of the most significant March heat waves in recorded history, with many locations running 20–30°F above normal and “so many records” being broken in a short span.