Unseasonable heat gripped the continental United States in March, making it the most abnormally hot month in 132 years of records, federal weather data has revealed.
Forecasts suggest a brewing El Nino could reach “superstrength,” further intensifying global warmth over the next year or so.
Not only was it the hottest March on record for the US, but the extent of its deviation from normal surpassed any other month in history for the Lower 48 states. March’s average temperature of 10.47 degrees Celsius (50.85 degrees Fahrenheit) was 5.19C (9.35F) above the 20th-century normal for the month.
This easily eclipsed the previous record of 4.9C (8.9F) set in March 2012, marking it as the most abnormally hot month on record, irrespective of the time of year, according to figures released by the National Oceanic and Atmospheric Administration (NOAA) on Wednesday.
The average maximum temperature for March was particularly high, at 6.3C (11.4F) above the 20th-century average, almost a degree warmer than the typical daytime high for April, NOAA noted.
Six of the nation’s top 10 most abnormally hot months have occurred within the last decade. February, which was 3.65C (6.57F) above the 20th-century normal, ranked as the tenth highest above normal.
“What we experienced in March across the United States was unprecedented,” said Climate Central meteorologist Shel Winkley. “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. But also this is coming on the heels of what was the worst snow year. And the hottest winter of record. So we’re seeing this continuation of extraordinary heat that took place during the winter months, continuing into the spring months as well. That’s where it’s really concerning, it’s just the duration of this heat.”
More than 19,800 daily temperature records were broken for heat across the country, according to meteorologist Guy Walton, who analyzes NOAA data.
A new study also found that marine heat waves are supercharging damage caused by hurricanes and tropical cyclones across the globe.
Researchers looked at 1,600 tropical cyclones — the broader category of storms that includes hurricanes — that made landfall since 1981 and found those that went over the extra-hot water were more likely to intensify rapidly, a problem that’s becoming more frequent. This resulted in 60% more disasters that caused at least $1 billion in damage — adjusted for inflation — when they hit land, according to a study in Friday’s journal Science Advances.
A better understanding of how marine heat waves amplify hurricanes could help forecasters, emergency officials and long-term planners prepare for future storms.
The study defined marine heat waves as long-lasting, large areas of water in the top 10% of historical heat. They are becoming more of a danger with climate change and ever hotter oceans, study authors said. Warm water is fuel for hurricanes.
“These marine heat waves affect more than half of landfalling tropical cyclones,” said study co-author Gregory Foltz, an oceanographer at the National Oceanic and Atmospheric Administration. “They’re happening closer to land and more frequently, so I think people need to pay attention and know that these are more likely to result in extreme damages when they make landfall.”
It’s important for meteorologists forecasting the storm track to see if these hurricanes go over a marine heat wave because it is more likely to intensify rapidly which “can potentially have a bigger impact on landfall,” Foltz said.
Just look at damaging hurricanes that smacked the United States in 2023, said study co-author Hamed Moftakhari, a coastal engineering professor who studies compound hazards at the University of Alabama.
“The story of Helene and Milton is that if you’ve got a warmer ocean, you’ve got the fuel to supercharge tropical cyclones even in a cascade. So within a few weeks you could get two rapidly intensified hurricanes making landfall in the west coast of Florida,” Moftakhari said. “This is shocking but should also be alarming for people.”
