A transformative shift is coming to the Bay Area weather forecast, with a sustained trend of record-breaking heat making way for brief, heavy downpours, chances of thunderstorms and plummeting temperatures.

“It’s kind of an overall pattern change,” Dylan Flynn, a meteorologist for the National Weather Service’s Bay Area office, told SFGATE on Sunday. 

The ridge of high pressure that led to weekend highs in the 80s is charting east as a trough of low pressure moves in from the Gulf of Alaska, remaining parked in the region for the whole week, Flynn said. By Wednesday, a cold front is on track to join it, delivering chances of rain for most of the Bay Area on Thursday and Friday. 

“Right now, it’s pretty uniformly distributed,” Flynn said. Coastal mountains could get up to an inch of precipitation while the rest of the Bay Area is slated to receive no more than a quarter of an inch. Flynn described the event as “more beneficial” than anything, leading to a cooldown that’s expected to finally bring temperatures down to seasonal averages.

One caveat is a 10 to 20% chance of thunderstorms. If the system does make landfall, it could lead to lightning strikes, localized, heavy downpours and some isolated flooding. However, “it’s tricky to pin down this far out,” Flynn said.

The cooler weather will also be particularly noticeable for people living along the coastline. Temperatures will dip by 10 degrees and into the 70s between Sunday and Monday before dropping into the 60s for the remainder of the week as thick clouds cover the sky. 

As far as the rest of April goes, Flynn said meteorologists are tracking “an active start to the weather pattern” for the first half of the month, with above-normal chances for precipitation. 

“It looks like we’re not going to get stuck in another death ridge,” he said. “We’ll have periodic cooldowns, with chances for rain, as we’re starting to eye the dry season. We’re not expecting to make up the deficit we got in March, but we should move in that direction.”

That said, if you’re looking to enjoy the lingering sunshine, now is the time to do it.

“There’s going to be a drastic change in the weather tomorrow,” Flynn said.