'Cool-down' gives Bay Area short reprieve from sweltering Labor Day weather

SAN FRANCISO -- It may only be for 24 hours or so, but Bay Area residents got a short reprieve Friday from the triple digit heat that a has toasted other regions of California.

A layer of fog rolled through the Golden Gate Bridge, stirring up cooling morning breezes along the San Francisco Bay shoreline and keeping the heat wave in check.

The National Weather Service said temperatures will remain 5-10 degrees above seasonal averages through Saturday. Then the heat up begins in earnest.

ALSO READ: Spare the Air Alert issued for Bay Area amid forecast heat Saturday

"This heat event is a marathon and not a sprint," forecasters said. "The peak of the heat still appears to occur later in the weekend and over Labor Day."   

 For local residents like Greg Meronek, the plans remain to stay out of the heat.  

"I'm not a big fan of the heat,"  Meronek told KPIX. "So, we're going to stay inside. We have an air conditioner, portable air conditioner that we're going to use."

With the holiday weekend comes more planned family outdoor activities. In the East Bay, open space parks in Walnut Creek are closed through the Labor Day weekend, as the region braces for several days of extreme heat.

"This is not the weekend to hike in the wildland environment," said Contra Costa County Deputy Fire Chief Aaron McAlister. "We're trying to eliminate risk this weekend when it's going to be over 100 degrees for multiple days."

The soaring temperatures will be threatening in a variety of other ways, but particularly for kids and pets left in vehicles. It's a threat that CHP Capt. Chris Sherry didn't mince words about.

"The @CHPDublin is offering free broken windows to anyone leaving children or pets in a hot vehicle," he tweeted.

The weather service also sent out tips to surviving the heat wave.

• Avoid outdoor activities during the hottest portion of the day,
• Stay hydrated and take frequent cooling breaks in the shade.
• Check on relatives, neighbors and friends who may not have access to adequate cooling.
• Use air conditioning where possible.
  

Forecasters said over the three-day weekend, temperatures will not drop off significantly overnight. The constant exposure to heat will carry with it heath dangers.

"So if you let your home get really hot and that it can't cool off, that could be a risk to be exposed to that heat for a long period of time," said UCSF associate professor of medicine Dr. Anna Chodos.

She said to be aware of the signs of dangerous heat exhaustion and exposure. They include: dizziness, strange behavior, fainting, cramping, nausea and vomiting.

 The lack of an overnight cooldown has other impacts -- mainly on electric grid transformers.

"They get hot in the hot weather," explained Severin Borenstein, an energy expert at UC Berkeley who sits on the board of governors at Cal ISO, the state's power grid manager.

Borenstein says many of the transformers atop utility poles are engineered with overnight cooling in mind.

"If the temperature stays high overnight, they don't cool down as much and the problem is, that can lead to more overheating and blown transformers," Borenstein said.

Cal ISO officials have extended its Flex Alert into Friday, calling on residents to continue conserving electricity during the current heat wave gripping the Bay Area and the state.  

The Flex Alert goes in effect from 4 p.m. to 9 p.m.

Officials are urging consumers to reduce use of electricity from during those times when there is most stress on the grid and solar energy production is declining. Meaningful consumer conservation during Wednesday's Flex Alert reduced the stress on the state's energy grid and keep the system balanced, officials said.