U.S. Experiences Most Abnormally Hot Month on Record in March
March 2025 delivered such persistent and unseasonable heat across the continental United States that it became the most abnormally hot month in 132 years of federal weather records. According to data released by the National Oceanic and Atmospheric Administration (NOAA), the average temperature for March reached 50.85 degrees Fahrenheit (10.47 degrees Celsius), which is a staggering 9.35°F (5.19°C) above the 20th-century normal for the month.
This figure easily surpassed the previous record of 8.9°F (4.9°C) set in March 2012, making it the most abnormally hot month ever recorded in the Lower 48 states, regardless of the time of year. The average maximum temperature was particularly extreme, soaring 11.4°F (6.3°C) above the 20th-century average—almost a degree warmer than the typical daytime high for April.
Record-Breaking Trends and Climate Concerns
Six of the nation's top ten most abnormally hot months have occurred within the last decade, with February 2025 ranking as the tenth highest above normal at 6.57°F (3.65°C) above average. Shel Winkley, a meteorologist with the nonprofit science research group Climate Central, described the March heat as "unprecedented" and expressed deep concern over the sheer volume of records broken.
"One reason that's so concerning is just the sheer volume of records, all-time records that were set and broken during that time period," Winkley emphasized. "But also this is coming on the heels of what was the worst snow year and the hottest winter of record."
From April 2025 to March 2026, the continental U.S. experienced its warmest 12-month period on record. Climate Central calculated that on March 20 and 21, about one-third of the nation endured unseasonable heat that would have been virtually impossible without human-caused climate change.
Meteorologist Guy Walton, who analyzes NOAA data, reported that more than 19,800 daily temperature records were broken for heat across the country last month. Additionally, over 2,000 locations set monthly heat records—a more challenging feat than daily records—surpassing the total number of March heat records set in entire decades of the past.
Jeff Masters of Yale Climate Connections starkly noted, "All those broken records tells us that climate change is kicking our butts." He also highlighted that the January through March period was the driest on record for the contiguous U.S., creating a dangerous combination for water availability, agriculture, river levels, and navigation.
Super El Niño Forecast to Intensify Global Warming
The next year or so is poised to escalate global warmth even further, as forecasts from both the European climate service Copernicus and NOAA predict a brewing El Niño will reach super strength. Meteorologists anticipate this phenomenon will increase already elevated temperatures worldwide, potentially surpassing the hottest year mark set by 2024.
An El Niño is a natural, temporary warming of parts of the central Pacific that alters global weather patterns. It forms when ocean temperatures are 0.5 degrees Celsius (0.9°F) above normal, with moderate strength at 1°C and strong at 1.5°C. Current forecasts project this El Niño to exceed 2°C, entering an informal "super-sized" category that could rival records from 2015 and 2016.
Victor Gensini, a meteorology professor at Northern Illinois University, explained that El Niño releases heat stored in the upper ocean into the air, causing global temperatures to rise with a lag of a few months. "A strong El Niño could plausibly push global temperatures to new record levels in late 2026 and into 2027," Gensini stated.
Long-Term Impacts and Climate Shifts
Super-sized El Niños often trigger a "climate regime shift," pushing normal conditions into a different pattern for years or decades, according to a December 2024 study in the journal Nature Communications. The study noted that after the 2015-2016 El Niño, the Gulf of Mexico jumped to a new sustained level of warmth, which may have contributed to stronger hurricanes along the Gulf Coast in subsequent years.
Growing research suggests that global warming from burning fossil fuels could be making El Niños stronger, though climate scientists caution this is not yet a consensus. Jonathan Overpeck, environment dean and climate scientist at the University of Michigan, remarked, "Global warming is supercharging El Niños and the atmospheric warming they drive. We saw this in 2016 and more recently in 2023. We're likely to see another jump in global temperatures if a strong El Niño develops later this year as being predicted."
While El Niños tend to reduce hurricane activity in the Atlantic, they can ramp it up in the Pacific and potentially ease drought conditions in the southwestern U.S., Masters added.
