Red flag warning issued for the North Bay mountains.

A break from the wickedly warm temperatures came the Bay Area’s way on Monday, but that did little to ease the fire concerns in certain parts of the region.

The National Weather Service had issued a red flag warning lasting from 11 p.m. Monday until 8 a.m. Wednesday for the North Bay mountains, particularly in northeast Napa County, meteorologist Gerry Diaz said late Monday morning. The warning upgrades a previous fire weather watch, with offshore winds expected to blow from 10 to 25 mph and gust up to 40 mph, the weather service said.

“We are really expecting those winds to pick up overnight,” Diaz said. “Going into the next few days, the air mass is going to dry out and more and more, and there’s going to be this burst of winds, followed by second and third bursts later in the week.”

The longer- term forecast brought a new fire weather watch for Wednesday evening into Friday morning, Diaz said, with areas of concern including the East Bay hills and the Santa Cruz mountains, along with the North Bay mountains, he said.

“The main concern there is just really dry conditions,” Diaz said.

At least the thermometer seemed to be cooperating Monday. The hottest spots in the Bay Area — Livermore, Antioch and the Almaden Valley — were expected to top out in the high 80s to very low 90s, a dip of about 3- 4 degrees from Sunday and 8-10 degrees from Saturday, when heat records were set in San Jose (95), San Francisco (93) and Napa (96).

A shallow marine layer brought fog late Sunday night and helped cool down the region, according to the weather service.

The temperatures will begin to reverse course on Tuesday, according to forecasters, but the heat is not expected to approach that of the past three heat waves.

“It’s going to be a very subtle warm-up over the next couple of days,” Diaz said. “It’s not going to be a huge difference in what we’re seeing (Monday). Maybe a couple of degrees.”