Bay Area weather ‘a bit odd,’ but cool clearing expected

In just a few hours Tuesday, the Bay Area weather showed an array of looks. For a while, the skies turned gray and even a bit steamy, with a bit of unusual mugginess. In some area, droplets fell lightly, barely wetting the ground.

And then, for a brief spell, there was even clear blue sky amid a shining sun.

“It’s a bit odd,” National Weather Service meteorologist Dial Hoang said Tuesday. “But we’re gonna be moving back to a more typical summer pattern.”

That switch was already underway by Tuesday afternoon and would continue Wednesday, he said. A low-pressure system that was crossing through Southern California gradually continued to migrate east, taking with it the stormy bands that carried enough moisture to dump some rain in the region.

It mostly was not measurable, but it did bring more than one patch of thunder and lightning, according to the weather service. Most of those thunderstorms were off the coast, “though we did see some of it reach land on the Central Coast,” Hoang said.

The weather service noted the storms over the coast were severe enough that they issued a “marine weather statement” to highlight the hazards for anyone on the water.

As for the rain, it showed up only as scattered drizzle in much of the region. About a tenth of an inch fell in areas of Sonoma and Marin counties, as it did in areas in Alameda and San Mateo counties.

In other places, Hoang said the totals were measured in the hundredths of inches.

The unsettled start to June and the fog that often accompanies it — technically the beginning to meteorological summer, ahead of the June 21 astronomical start of the season — have complex origins in both the differences in temperature between the Pacific Ocean and the air above, and in the water vapor drifting down from the snow-covered Sierra Nevada.

In the current pattern, Hoang said, a return to clear, sunny weather will be next, with clouds early in the morning that clear off and then return in the evening. But that return to sunny weather will not mean a return to hot temperatures.

The temperature in the interior regions of the East Bay and in the Santa Clara Valley are expected to top out in the mid- to upper-70s. In Alameda County and other Bayshore areas, it’s expected to top out in the lower 70s. The Peninsula and San Francisco likely won’t rise out of the 60s.

“We’re under the influence of a larger upper-level trough,” Hoang said. “That influence is going to keep the temperatures down for the time being, really for quite a while.”