Trending Now - Western US Experiences Record-breaking March Heatwave
WHO:
AccuWeather, The Guardian, USA Today
Tyler Roys, Senior Meteorologist at AccuWeather
Ben Clarke, extreme weather and climate change researcher at Imperial College London
Friederike Otto, climate science professor at Imperial College London
National Weather Service
WHAT:
A heat wave is occurring across the western U.S., with temperatures 15–30 degrees above normal.
Martinez Lake, Arizona, recorded the highest temperature ever in March in the U.S. at 110 degrees on March 19th, 2026.
Phoenix, Arizona, reached 105 degrees on March 19th, breaking the previous record of 97 degrees set in 2017.
Downtown Los Angeles recorded 98 degrees on March 17th, breaking a record of 94 degrees set in 1914.
San Francisco tied its all-time March record high of 70 degrees on March 17th, first set in 1952.
Palm Springs, California, set a new all-time March record high of 106 degrees on March 18th and broke it again with 107 degrees on March 19th.
Las Vegas set an all-time March high of 94 degrees on March 18th and reached 95 degrees on March 19th.
Over 18 million Americans were under extreme heat warnings on March 20th, 2026.
WHERE:
Western United States, including California, Arizona, Nevada, New Mexico, Colorado, Oregon, Idaho, and Wyoming.
Martinez Lake, Arizona, near Yuma.
Downtown Los Angeles, California.
San Francisco, California.
Palm Springs, California.
Las Vegas, Nevada.
Phoenix, Arizona.
WHEN:
The heat wave began earlier in the week of March 16th to March 20th, 2026.
Martinez Lake recorded 110 degrees on March 19th, 2026.
Phoenix reached 105 degrees on March 19th, 2026.
Downtown Los Angeles recorded 98 degrees on March 17th, 2026.
San Francisco tied its record on March 17th, 2026.
Palm Springs set records on March 18th and 19th, 2026.
Las Vegas set records on March 18th and 19th, 2026.
Over 18 million Americans were under extreme heat warnings on March 20th, 2026.
WHY:
The heat wave is driven by a massive area of high pressure, creating a "heat dome" that suppresses cloud formation and rainfall.
Scientists state that the climate crisis has made such heatwaves four times more likely over the last decade.
HOW:
The analysis of the heat wave was conducted by examining weather and forecast data and using climate model simulations to compare changes in heat events.
The National Weather Service reported the extreme temperatures and issued heat warnings across affected regions.
(UPDATED March 20, 2026 17:18 UTC)
A significant heat wave is currently sweeping across the western U.S., with temperatures soaring 15 to 30 degrees above normal, prompting extreme heat warnings for over 18 million Americans. Martinez Lake in Arizona recorded a staggering 110 degrees on March 19, marking the highest temperature ever recorded in March in the U.S., while Phoenix also broke its previous record with a high of 105 degrees the same day. This heat wave, driven by a massive area of high pressure creating a "heat dome," has made such extreme temperatures four times more likely due to the ongoing climate crisis.