Historic March heatwave
A massive heat dome is smashing March records across the Southwest — Phoenix is forecast to hit 100–101°F for several days and nearly 180 cities have seen record temperatures so far ( ). Event organizers are already adjusting plans and public‑health warnings are in place as the extreme heat persists (azcentral.com).
Phoenix reached 105°F on March 19, 2026 — topping the previous mark for that date and marking one of the earliest triple‑digit readings on record for the city. (azcentral.com) Four weather stations — two in Arizona and two in California — recorded 112°F on March 20, 2026, establishing a new highest temperature ever observed in the continental U.S. for the month of March. (wtop.com) Martinez Lake and other desert sites near Yuma logged readings of 110°F on March 19–20, 2026, contributing to a string of unprecedented early‑season highs across the lower Colorado River region. (kjzz.org) The National Weather Service issued Extreme Heat Warnings for central and southern Arizona for March 19–22, 2026, and forecasters said the pattern could produce more than 200 record‑high readings nationwide during the event. (weather.gov) (insideclimatenews.org) At the Luke Days Airshow in Glendale, officials reported more than 400 people treated for heat‑related illness and at least 25 hospitalizations as temperatures topped 100°F for multiple consecutive days. (abcnews.com) Local organizers and land managers made concrete adjustments: several popular Phoenix hiking trails were temporarily closed in mid‑March for the first time in memory, and multiple spring festivals and tourist attractions altered schedules or moved activities indoors. (12news.com) (axios.com) Maricopa County and the state launched public heat‑safety communications and pointed residents to cooling resources and 2‑1‑1 support during the episode, while county pages noted Extreme Heat Warning periods and guidance for vulnerable populations. (maricopa.gov)
