A key sign of hurricane activity has flipped into high gear

Hurricanes need warm ocean water to form, and water temperatures in a key section of the Atlantic are really starting to warm up.

"One of the biggest changes I’ve observed in recent weeks is a considerable warming of the so-called Main Development Region (MDR) of the Atlantic above its seasonal averages," WPLG-TV hurricane expert Michael Lowry said in late July on a Substack post.

That's a big change from earlier this season.

"To open the hurricane season in June, waters across this bellwether part of the Atlantic where most of our strongest hurricanes get their start were running average to even below average," he said.

The Main Development Region (MDR), located between the Caribbean and Africa, is a region in the Atlantic where many tropical cyclones (tropical storms and hurricanes) form. This area is key because it's where many tropical waves, which can develop into hurricanes, originally form.