With weather conditions ripe for the rapid spread of fire, a red flag warning is in effect Thursday from 9 a.m. to 8 p.m., the National Weather Service said.
Such a warning indicates that "critical fire weather conditions are expected or occurring," the service said.
Northwesterly winds of 15 to 25 mph and gusts around 40 mph are expected Thursday, with relative humidity as low as 18 percent, the service said.
Compared with relative humidity Wednesday in the mid-40 percent range, 18 percent is considered "very low," said John Murray, a weather service meteorologist in Upton.
For Wednesday, a special weather statement said that high winds, combined with dry ground cover and low humidity would "result in conditions favorable for the rapid spread of brush fires."
Indeed, a Flanders brush fire started about 3:30 p.m. in the woods off Pleasure Drive, a local fire official said. Four departments -- Flanders, Riverhead, East Quogue and Hamptons Bay -- brought the fire under control an hour later.
Along with the predicted dry air and wind gusts for Thursday come expectations for Island temperatures in the upper 50s to low 60s, the service said.
People should take special care when disposing of any burning material, such as cigarette butts, Murray said.
And the service advised contacting authorities right away should a fire or smoke plume be spotted.