The National Weather Service has issued an excessive heat watch for most of the San Francisco Bay Area for Tuesday and Wednesday, with temperatures in the big cities of particular concern, a meteorologist said.
Warm temperatures from Sunday and Monday will turn to really hot on Tuesday and Wednesday, with degrees in the mid-80s to 90s near the coast and mid-90s to 103 inland, according to Ryan Walbrun, senior meteorologist for the weather service in Monterey.
Meanwhile, a second consecutive Spare the Air day has been issued in the Bay Area for Tuesday because forecasted high temperatures and low winds are expected to create unhealthy smog levels, air quality officials said.
The high heat conditions will come from a ridge of high pressure with easterly and northeasterly winds blowing hot air towards the Bay Area from the Nevada desert and only light cooling winds from the ocean, Walburn said.
"Think of it as a big warm area coming over the region," Walburn said.
The excessive heat watch will start at 1 p.m. on Tuesday and continue to 8 p.m. Wednesday, according to Walburn.
The two-day heat warning will be of biggest concern in San Francisco, Oakland and San Jose that are densely populated and not many people have air conditioning to cool off with, he said.
A lot of residents are just not used to handling such hot weather and heat lingering in their homes for 24 to 48 hours in May, Walburn said.
"It's the sudden change from 60 to 65 degrees to 95," he said. "It can be somewhat hard for someone who is elderly to deal with that."
The heat wave will subside some on Thursday, which will still be a warm day, with highs that might be in the 90s in the East Bay.
On Friday, the Bay Area should see a return to temperatures in the 70s and 80s, which are seasonable for this time of year, Walburn said.
In the meantime, the Bay Area Air Quality Management District has declared Tuesday as its second Spare the Air day of its summer season after the first was issued for Monday.
Commuters are urged to avoid driving alone on Spare the Air days to cut down on the amount of car exhaust entering the atmosphere, according to the air district.
"Vehicle traffic accounts for most of the ozone-forming pollution in the Bay Area, and choosing commute alternatives such as carpooling or taking transit can make a big difference when it comes to protecting air quality and our health," air district spokesman Jack Broadbent said in a statement.
The air district said 37% of Bay Area employees commute alone to work every day and that employees are more likely to adopt alternatives if encouraged by their employer.
High levels of ozone can cause numerous health problems including throat irritation, congestion, chest pain, asthma and worsened bronchitis and emphysema, according to the air district.
Air pollution is particularly harmful to young children and seniors, district officials said.