The "red flag warning" for brush fire conditions has been lifted for Long Island and New York City, the National Weather Service said Tuesday evening.

By midnight, lighter winds and rising humidity levels will replace the dry air and strong wind gusts -- a combination of factors that fuels fires, said meteorologist David Stark at the Upton-based service.

The warning was lifted at 6 p.m. It is issued when the humidity level falls below 30 percent and wind gusts frequently exceed 25 mph.

At 6 p.m. Tuesday, the humidity was 15 percent and gusts had died to about 20 mph or less, he said.

That made conditions for runaway fires less favorable, meteorologists said.

On Wednesday, the temperature should reach the upper 50s, with rain possible, while the relative humidity should exceed 50 percent, Stark said. Winds gusts will remain under 20 mph, the service said.

The red flag warning had been in effect earlier Tuesday, which means "critical fire weather conditions are expected or occurring" in the area and that "a combination of strong winds, low humidity and dry fuels will create explosive growth potential" for fire, the weather service said in a statement issued at 3:26 a.m.

Meteorologists had advised residents to use "extreme caution" with any outdoor burning and even with the disposal of smoking materials.

Regional weather service observational program leader Tim Morrin said that "unusually dry" conditions had led to the warning and noted the humidity has been so low that, despite freezing temperatures overnight, Long Island didn't see frost -- a rare occurrence.

"It's so dry," Morrin said, "that we did have a freeze, but no frost. It was really unusually dry with very low humidity."

In fact, the overnight lows were in the upper 20s -- including 29 degrees in Islip and 28 degrees in Upton -- which is a far cry from last week, when temperatures soared into the 70s and lows were in the 40s.

Wind gusts were in the mid-40-mph range Monday, as well, and overnight wind chill temperatures were in the 15- to 20-degree range, Morrin said.

The weather service said that high-wind gusts in Nassau on Monday were recorded in Glen Cove (46 mph) and Lido Beach (45 mph), with eight communities in Suffolk breaking the 40-mph barrier.

Those locations were: East Farmingdale and Long Island MacArthur Airport in Ronkonkoma at 46 mph; Stony Brook and Brookhaven Airport in Shirley at 45 mph; Patchogue and Westhampton Beach at 44 mph; Eatons Neck at 42 mph; and East Moriches at 41 mph.