Giving another voice to just how intense next week’s heat wave is likely to be, the National Weather Service on Friday afternoon issued an excessive heat watch set to begin Tuesday morning for most of the Bay Area.
The NWS warned in the bulletin that there will be “dangerously hot” temperatures with limited overnight cooling. Temperatures are expected to peak in Livermore and Concord, with both cities predicted to hit 103 on Tuesday and one degree higher on Wednesday.
Temperatures are likely to hit the mid- to high 90s in Fremont, San Jose, Santa Rosa and Napa on those hottest days. Hayward, Redwood City and Sunnyvale will be in the low 90s, with 80s in many other cities, including Oakland.
“It’s going to be hot for a really long time,” said NWS meteorologist Nicole Sarment. “The main thing is it’s not just going to be a one day event. We are talking six, seven days of it.”
Because of those warmer-than-usual overnight lows, there will be little relief from the heat even when the sun goes down, particularly in interior areas and elevated terrain.
The impacts of the heat compound when it does not cool down overnight, Sarment said, leading to warmer starting temperatures the next morning. Generally, it will be about 10 degrees hotter overnight than usual, she added.
“The body is more taxed because you don’t get that break overnight,” Sarment said, adding that residents should be mindful of opening and closing their windows.
The warning will in effect for areas across the Bay Area and Central Coast that are not directly coastal, according to the release. It was set to expire on the evening of July 5, although temperatures will begin falling by July 4, according to the forecast.
The NWS was also emphasizing the potential fire danger next week’s conditions will bring, Sarment said. The heat combined with dry and windy weather create the ideal conditions for a fire, and with the Fourth of July, officials are concerned about fireworks sparking blazes.
“Don’t even use fireworks this year — that’s how bad conditions are going to be next week,” Sarment said. “One less spark, one less wildfire.”
Experts warned that these elevated temperatures raise the possibility of heat related illnesses, especially for people working outdoors. The NWS advised that people drink plenty of fluids, avoid the sun, stay in air conditioning and check in with relatives and neighbors. They also added that children and pets should not be left in cars unattended, as cars can reach lethal temperatures very quickly.
Sarment added that while temperatures are likely to be more temperate along the coast, there will not be much relief from the heat.
Over the weekend, temperatures will begin to warm up but not to the level of next week. San Jose will see temperatures into the mid to high 80s and Walnut Creek will see temperatures close to 90 both Saturday and Sunday. Oakland has more temperate highs, with forecasts predicting 78 for both Saturday and Sunday. San Francisco will see highs that reach only to the low 70s.