NAHUNTA, Ga. (AP) — Wildfires burning across the southeastern U.S. were intensifying Wednesday after destroying nearly 50 homes in Georgia and forcing evacuations and school closures in some communities.

Some of the biggest blazes were along Georgia’s coast and between and around Jacksonville, Florida, a state that is facing one of its worst fire seasons in decades. It was not yet clear how the wildfires started, but a long drought, low humidity, and strong winds were fueling them.

Georgia’s two biggest wildfires together have burned more than 31 square miles (80 square kilometers), and at least four other smaller fires have been reported in the state. The area of the state where the worst fires were burning is in exceptional or extreme drought, the most dire levels, according to the U.S. Drought Monitor.

In southeast Georgia, the fast-moving Brantley County fire was threatening more homes Wednesday after destroying 47 a day earlier, according to Joey Cason, the county manager. That fire grew in size by roughly six times in just half a day on Tuesday. Nearly two dozen fire agencies were helping fight the blaze, Cason said at a news conference Wednesday.

Brantley County Sheriff Len Davis warned residents to be ready to evacuate, noting that the winds could shift rapidly and unexpectedly. At least 800 evacuations have taken place in the county and five shelters have opened, as the fire threatens 300 more homes, the Federal Emergency Management Agency said.

Another large fire in Clinch County forced evacuations in multiple communities, with the Georgia Forestry Association labeling the situation as serious and evolving. Firefighters in Florida were battling 131 wildfires that had burned 34 square miles (88 square kilometers) mostly in the state’s northern half.

Firefighting resources are being allocated throughout the state. Florida Commissioner of Agriculture Wilton Simpson remarked, Florida has got one of the worst fire seasons in maybe the last 30 or 40 years. A wildfire caused disruptions to Amtrak train services in northeast Florida, but normal services resumed on Wednesday.

Smoke from the fires impacted air quality across several regions, including Atlanta and Jacksonville, with areas in south Georgia reaching unhealthy air conditions. The National Weather Service reported that the combination of low humidity and breezy winds would maintain high fire risk levels through the week. Residents are urged to stay vigilant as firefighting efforts continue amid worsening conditions.