As temperatures in the 90s cooked the Bay Area on Thursday, weather forecasters urged residents to fetch their sweaters, jackets, raincoats and umbrellas.

The change that’s coming today is that significant.

“Things are moving along as we expected,” National Weather Service meteorologist Alexis Clouser said Thursday afternoon.

All of which means that by today, the region will have seen the last of its significant heat — perhaps for the rest of the year, forecasters said.

A low-pressure system moving north from Baja is expected to replace the final part of high pressure that hung around the region Thursday and pushed temperatures into territory that were expected to threaten heat records. That low pressure is expected to drop temperatures by 15 to 20 degrees throughout the region starting today.

The hottest spots in the region — Brentwood and Concord in eastern and central Contra Costa County; Livermore in Alameda County; and Morgan Hill in Santa Clara County — were expected to peak between 93 and 98 degrees Thursday afternoon. Today, the temperatures in those cities were not expected to rise above 84.

By Saturday, rain could be falling as another cold-pressure system — this one from the Pacific Northwest and more similar to winter-like patterns — descends into the region.

Confidence was at about 30% for rain by Saturday throughout most of the Bay Area, according to NWS forecasters. That possibility will jump to 60% on Sunday.

With the rain, temperatures in the low 70s and mid- to high 60s were predicted to follow.

“We have another low-pressure system following the high pressure,” NWS meteorologist Chrystal Oudit said. “It’s not unusual.”

The cool air will come after a scorching day that forecasters said could be the last real hot one of 2023.

Several highs on Thursday were likely to threaten records, forecasters said. Those included Santa Rosa’s prediction of 95 (against a record of 95 in 1921), San Jose’s 95 (91 in 1913), Half Moon Bay’s 88 (82 in 1998), Downtown San Francisco’s 90 (90 in 1992) and SFO at 92 (86 in 2022).

Other Bay Area forecast highs included 93 in Concord, 94 in Livermore, 90 in Santa Cruz, 94 in Palo Alto, 100 in Gilroy and 91 in Oakland.

Clouser said no records fell before 3 p.m., but that any official records that were set likely wouldn’t be known until much later Thursday night.

Those hot temperatures were warmer than they were on a Wednesday that saw San Francisco International Airport tie its 2022 record temperature with a high of 86.

The two-day heat wave that left pumpkin patch attendees clinging to blotches of shade Wednesday only ramped up on Thursday with triple-digit potential in the forecasts.

The NWS’s heat advisory remained in effect until 11 p.m. Thursday, after being issued Wednesday. The advisory warns people to drink excessive fluids when outdoors and to exercise caution in the extreme heat.

The Bay Area Air Quality Management District also put into effect the year’s 11th Spare the Air Alert on Thursday. The alert called for the ban of all wood burning except in specialized situations. The district measured the air quality through most of the region as moderately unhealthful.