Bay Area's muggy weather to linger into midweek

Tropical moisture brought muggy weather to the Bay Area this week, resulting in some unusual dew points and high temperatures.

Marin’s hottest days — Monday and Tuesday — were expected to bring highs ranging from the low- to mid-70s to the upper 90s, but it is the humid air that tells the story, said Dalton Behringer, a meteorologist with the National Weather Service.

“This excess moisture will hang around for the next couple days,” he said.

Slight chance for light showers through the evening today as upper low continues to draw in midlevel moisture to the Bay Area and Central Coast.

It's also going to be another hot day inland, so be sure to practice heat safety! #CAwx pic.twitter.com/TWZyG1vpMM

— NWS Bay Area 🌉 (@NWSBayArea) August 14, 2023

Behringer said the dew point can be a better indicator than relative humidity for how warm it feels, especially with the presence of the marine layer.

The dew point is the temperature the air must be cooled to in order for the air to be saturated with water vapor; the higher the dew point, the more humid it can feel. The dew point for Marin is in the low to mid 60s.

“It’s not out of the norm for the area at this time of year,” Behringer said. “But a dew point in the 50s is more likely for us, with an occasional spike into the 60s. A dew point in the 60s is more normal for the Great Plains.”

The humid conditions, from the final remnants of a tropical storm that started far off the coast of Baja California and never became as strong as expected, are expected to remain until Wednesday afternoon.

Most of Marin will see highs around the mid 80s to low 90s, and the coast will remain in the 70s. Thursday’s temperatures are projected to be about the same, with Friday cooling to the lower 80s in most parts of the county.

The topical weather brings with it a risk of lightning and light rain, forecasters said.

While chances were slight, the National Weather Service forecasts showed a chance of precipitation to pair with high temperatures.

⚡GOES GLM data is showing a few flashes along the Contra Costa County line. Thunder roars, go indoors! #cawx pic.twitter.com/Di4XSdHXak

— NWS Bay Area 🌉 (@NWSBayArea) August 14, 2023

The higher temperatures were also likely to put a strain on the state’s power grid. In a statement, PG&E encouraged customers to set their thermostat to 78 degrees between 4 and 9 p.m. to reduce energy usage. The California Independent System Operator, which monitors the state’s power supply, was expected to have enough electricity statewide to meet the higher demand.

The NWS issued a moderate heat risk alert through Tuesday, warning residents to avoid strenuous outdoor activity and not to leave children and pets inside parked vehicles. The high temperatures should affect most people that are sensitive to heat — especially those with insufficient cooling and hydration systems at home, forecasters said.

The temperatures rose just after a string of thunderstorms hit parts of the East Bay on Sunday night. Lightning strikes were reported in Walnut Grove, Discovery Bay and just south of Buchanan Field Airport in Concord, according to the NWS. At Oakland International Airport, winds were reported gusting to 40 mph.

The Bay Area News Group contributed to this report.

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