Hurricane Harvey, which devastated South Texas last August, was powered by what scientists say were the highest ocean temperatures they've ever seen in the Gulf of Mexico.
Portions of the Gulf to the south of the Texas coast were 86 degrees Fahrenheit. That's several degrees higher than normal — and it's heat that drives big storms.
Kevin Trenberth, an atmospheric scientist at the National Center for Atmospheric Research, says the extraordinarily high heat lasted for several days before the storm. "Record high ocean heat values not only increased the fuel available to sustain and intensify Harvey," he says, "but also increased its flooding rains on land."