Hurricane Idalia rapidly intensified Tuesday evening into Wednesday morning and maxed out as dangerous Category 4 before weakening slightly ahead of landfall. It did so as it tapped into some of the warmest waters on the planet, and joined a growing list of major storms like Hurricane Ian that rapidly intensified before landfall in recent years.
Rapid intensification is precisely what it sounds like — when a storm’s winds strengthen rapidly over a short amount of time. Scientists have defined it as a wind speed increase of at least 35 mph in 24 hours or less.
Scientists have been alarmed at how warm ocean temperatures have been this year, including in the Gulf if Mexico and around southern Florida, where sea surface temperature climbed to around 100 degrees Fahrenheit earlier this summer.
Average sea surface temperature in Idalia’s path was recently measured at nearly 88 degrees Fahrenheit — a record there since data began in the early 1980s.
In the Gulf overall, ocean temperatures are around “1 to 2 degrees Celsius (roughly 2 to 3.5 degrees Fahrenheit) above normal for this time of year, which is a lot when you consider this is already a super-hot time of year,” Brian McNoldy, an atmospheric scientist at the University of Miami, told CNN. “With that in mind, and with those extra warm waters ahead of it, it does make rapid intensification more likely to happen.”
Idalia did weaken slightly to a Category 3 before landfall, “but too late and not enough to make a difference” in the impacts, McNoldy posted on social media Wednesday morning.
Rapid intensification has been happening to more storms as they approach landfall, making them harder to prepare for and more dangerous to the people who stayed behind expecting a weaker storm.
It’s just one of the ways experts say the climate crisis is making hurricanes more dangerous, as warmer waters allow for storms to strengthen quicker. More than 90% of the planet’s warming in the past 50 years has taken place in the oceans, according to the National Oceanic and Atmospheric Administration.