March’s persistent unseasonable heat broke multiple records across the continental United States, according to federal weather data released by the National Oceanic and Atmospheric Administration. NOAA said the country recorded its most abnormally hot month in 132 years, and that the month’s average temperature and departure from the 20th-century norm surpassed all previous March records on recordkeeping that date back more than a century.
NOAA reported that the continental U.S. averaged 50.85 degrees Fahrenheit (10.47 C) in March, which was 9.35 F (5.19 C) above the 20th-century normal for March. The agency said that margin above normal beat the prior record by amount, a level that had been set in March 2012, while NOAA also reported the average maximum temperature for March was especially high—11.4 F (6.3 C) above the 20th-century average.
The extreme warmth arrived on top of already-hot recent conditions, with NOAA data also indicating that April 2025 to March 2026 marked the warmest 12-month period on record for the continental United States. NOAA said this was paired with a particularly dry stretch as well: the January through March period was the driest on record for the contiguous U.S., a circumstance Jeff Masters of Yale Climate Connections said creates a “bad combination” for water availability, agriculture, river levels and navigation.
Meteorologists pointed to the volume of record-setting warmth as a sign the heat was not just widespread but relentless. Shel Winkley, a meteorologist with Climate Central, said March was “unprecedented,” adding that the concern comes both from the “sheer volume of records” and from what he described as the backdrop of severe impacts, including the prior “worst snow year” and “hottest winter of record.” Guy Walton, who analyzes NOAA data, said more than 19,800 daily temperature records were broken for heat nationwide, and that more than 2,000 places set monthly heat records—numbers Walton said were harder to break than daily records.
Climate Central also calculated the likelihood that the unseasonable heat would have occurred without human-caused climate change. It said that on March 20 and 21, about one-third of the nation experienced heat that would have been virtually impossible without human-driven warming. Masters described the record-breaking pattern as evidence that climate change is compounding the conditions for extreme heat.
As the northern hemisphere moves toward summer and into fall, forecasters said an El Niño forming and strengthening could further raise global temperatures. The European climate and weather service Copernicus and NOAA are both forecasting a “super” strong El Niño expected to develop in the coming months and intensify into winter, with meteorologists expecting it to push past the hottest-year mark set by 2024.
El Niño is a natural, cyclical warming of parts of the central Pacific that alters weather across the planet, forecasters said, and it is defined by the degree of warming above normal in that region. Meteorologists said El Niño forms when a specific part of the ocean is 0.5 degrees Celsius (0.9 F) warmer than normal, and they described strength classifications at 1 degree Celsius for moderate and 1.5 degrees Celsius for strong. They said both Copernicus and NOAA are forecasting this event to be well above 2 degrees Celsius into a region informally called “super sized,” with conditions potentially rivaling those from 2015 and 2016.
Victor Gensini, a meteorology professor at Northern Illinois University, said El Niño releases heat stored in the upper ocean into the air, raising global temperatures with a few months’ lag time. He said, “A strong El Niño could plausibly push global temperatures to new record levels in late 2026 and into 2027.” University of Michigan climate scientist Jonathan Overpeck said a warming world can intensify the system that drives El Niño impacts, calling it “supercharging El Niños and the atmospheric warming they drive,” and noting that the pattern has appeared in prior events including 2016 and more recently in 2023.
Researchers also said super-sized El Niños can shift conditions for years. A study published last December in the journal Nature Communications found that after the 2015-2016 El Niño, the Gulf of Mexico jumped to a new sustained level of warmth that may have contributed to stronger hurricanes along the Gulf Coast in later years. The AP reported that while research suggests warming from burning coal, oil and natural gas could be making El Niños stronger, scientists said that point is not yet a consensus.
Scientists said the impacts of El Niño do not limit themselves to temperature. Masters said El Niños tend to tamp down hurricane activity in the Atlantic but ramp it up in the Pacific, and they could help ease the southwestern drought, depending on how the pattern evolves through the seasons.