A Bay Area heat wave that was expected to be fairly brief before turning longer and then stubbornly holding on a couple of days more than originally anticipated is finally, really, honestly set to make an exit.

So said the National Weather Service, but with a caveat.

“What you’re going to see (Monday) is just some relief,” NWS meteorologist Brayden Murdock said. “On Tuesday, there’s gonna be a lot more.”

The relief from the heat Monday will be primarily for those who live near the coast in the Peninsula and along the cities that run along Interstate 880, where the temperatures are expected to remain in the 70s. In the South Bay, temperatures will range from the low 80s (in San Jose and Santa Clara) to the high 80s (in Morgan Hill).

Only in the far interior of the East Bay are the temperatures expected to reach or surpass 90. The hottest spot is expected to be in Livermore, which was forecast to reach 92.

All of those temperatures are cooler than those that dotted the board in the previous week, when the thermometer often passed 100 in the interior and hills and the 90s and high 80s elsewhere.

A high-pressure system that has proven to be more stubborn than strong has caused the heat to hang out longer than originally expected, Murdock said.“If it was a strong system, it would’ve gotten a whole lot hotter,” he said. “It just didn’t have enough force coming at it or the winds to push it far enough out of the area to feel the difference.”

According to Murdock, that push already was under way on Monday morning. The marine layer was far less compressed, allowing relief from some of the dense fog that affected the Monterey Bay coastline and Northern Salinas Valley.

The winds also are were showing signs of shifting, he said.

Those factors are expected only to increase as a low-pressure trough from the Alaskan gulf moves through the region. That trough has been moving with a bit less speed and force than originally expected, according to Murdock.

“It’s finally going to get here,” he said of its anticipated Tuesday arrival. “From then on, our weather pattern is gonna keep us on the cool side for the foreseeable future.”