Several fire departments are working to contain a brush fire in Riverhead Saturday amid a red flag warning across Long Island, the Riverhead Town Police Department said.

The fire broke out on the east side of 3000 Sound Ave. and police responded around 12:30 a.m. Saturday. The Riverhead Fire Department is actively battling the blaze alongside 17 additional fire departments, police said in a news release.

The fire appears to be contained to the wooded area, police said.

The red flag warning is in effect until 6 p.m. Saturday, the National Weather Service said.

The alert is a combination of low humidity of 25% in the area and wind gusts expected to reach up to 30 mph throughout the afternoon, the weather service said.

“Those are two conditions that are considered there (on Long Island) to have the potential to spread wildfires if they were to start,” said NWS meteorologist David Stark. “If a fire were to break out, conditions could cause it to start very quickly.”

Winds are expected to ease Saturday evening, Stark said, and rain is forecast Sunday evening.

“This may be the first wet, measurable rain we’ve seen here, more than just a little bit in the last couple of months,” Stark said.

There will also be a Freeze Warning on Long Island, in effect from 10 p.m. Saturday until 9 a.m. Sunday. Temperatures are expected to drop as low as 29 degrees, which could pose a danger to some crops.

“It’s more for the agricultural side. It’s not the type of gel you need to protect the pipes,” Stark said. “If you have sensitive plants outside that a frost could potentially kill, they obviously need to be protected.”

Joshua Needelman covers the town of North Hempstead for Newsday. A Long Island native and graduate of the University of Maryland, his work has appeared in publications including the New York Times and the Washington Post.