SAN FRANCISCO (CBS SF) — A high pressure system edged toward the San Francisco Bay Area Saturday, carrying with it the promise of scorching temperatures, sweltering northeastern winds and an elevated threat of wildfires in the North Bay and the East Bay hills.

KPIX 5 meteorologist Darren Peck said there would be a significant jump in temperatures over the next 24 hours. San Francisco will go from a predicted high of 74 on Saturday to 89 on Sunday. Santa Rosa and Concord will soar from the low 90s to triple digits

“Monday technically will be the top of the heat wave, but Sunday is when it hits you in the face,” he said. “You are going to do a complete turnaround. It will feel very different.”

A National Weather Service Red Flag Fire Warning goes into effect Saturday at 9 p.m. and will remain in place until 11 a.m. Monday. The high temperatures, low humidity and gusty northeastern winds are conditions ripe for wildfires.

“The first shot of winds will come down the Sac Valley this evening,” the weather service said on Saturday. “Then as the night time inversions set-up the first burst of winds will reach the Napa hills sometime around 9-10 p.m. and then spread over the higher terrain of Sonoma County.”

“Northeast winds 10 to 20 mph with gusts to 25 mph will develop after midnight,” weather service forecasters added in their Red Flag Warning alert. “These dry winds will rapidly lower humidity values by sunrise Sunday. Persistent northeast winds during the day Sunday then a secondary burst Sunday night will drive all the way to the coast with local gusts 30-45 mph.”

Late Sunday night, humidity levels will dip into the teens.

“There will be no humidity recovery across the entire region,” forecasters said. “This will really dry out the fire fuels that have been protected by the marine layer the last few days.”

Hardly an encouraging prediction for a region that has already been decimated by wildfires triggered by a record heat wave in August and followed by a rare outbreak of dry lightning storms.

The CZU Lighting Complex fire burned 86,509 acres in the Santa Cruz Mountains and was finally fully contained this week. The LNU Lighning Complex fire, burning in Wine Country, is at 363,220 acres and is 98 percent contained but will get a blast of hot, windy conditions over the next 48 hours.

Meanwhile, the SCU Lightning Complex fire was at 396,624 acres and was at 98 percent contained.

The weather service the system will present the biggest wildfire threat to “all lower elevation unburned areas west of Highway 101 including around Mount Tamalpais as well as Point Reyes National Seashore. Any remaining heat in the Walbridge fire (part of the LNU Complex) may flare up as well.”