These Bay Area counties will experience jump in extreme heat days in coming decades, data shows

ByTim Didion, Lindsey Feingold, Maggie Green, Maia Rosenfeld KGO logo

Thursday, August 17, 2023

These Bay Area counties will see jump in extreme heat days by 2050

Weather data shows several Bay Area counties will experience a jump in extreme heat days in the coming decades due to climate change.

SAN FRANCISCO (KGO) -- While climate change affects all of us, new projections are highlighting the increasing stress on workers who do their jobs outdoors - and several Bay Area counties are going to be especially vulnerable in the coming decades.

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The ABC7 data journalism team analyzed data from the First Street Foundation, a nonprofit science and research group that studies climate risk data. It found the average U.S. county will see 13 more days per year with a heat index of 100 degrees Fahrenheit or higher. By 2050, weather data models show some communities will live with up to 131 days a year - more than one-third of the year - that feel like 100 degrees or warmer.

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In the Bay Area, most counties will see a rise in extreme heat days, where the outdoor heat index exceeds 90 degrees. Santa Clara County will experience more than 10 extra days above 90 degrees, jumping from 18 to 29 days. Other county hotspots will spike as well, including Contra Costa County from 27 days to 40 days, Napa County from 29 days to 45 days and Solano County from 37 days to 54 days.

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"Sometimes it does get a little hot out there. You know, you start the day off and it's pretty cold. And around 10 o'clock, it's already high 90s," said Victor Dominguez, a parks maintenance worker for Santa Clara County Parks Department, said.

But he says crews at Hellyer Park and other sites in Santa Clara County have a strategic plan in place before work on hot days even begins. This includes email alerts and tailgate safety meetings that cover everything from ensuring accessible supplies of drinking water to heat relief.

"Maybe we'll take a sooner break or we'll even do the majority of the hard labor tasks and jobs more towards the beginning of the shift," Dominguez said.

While most other Bay Area counties will also experience heat increases, experts say the most vulnerable locations often have the highest percentage of people working outdoors.

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According to the U.S. Bureau of Labor Statistics, 15% of the Napa County worker population spends the majority of their time outdoors. Sonoma County is the next highest at 10%, with Solano and Marin counties following at 7% each. Santa Clara County's outdoor worker population is 6%.

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Santa Clara County's heat preparation for park workers is important because the CDC found "hot weather is associated with an increase in heat-related illnesses, including cardiovascular and respiratory complications, renal failure, electrolyte imbalance, kidney stones, negative impacts on fetal health, and preterm birth."

According to the Agency for Health Care Research and Quality's Healthcare Cost and Utilization Project, in California, there were 16.6 heat-related ER visits per 100,000 people in 2019.

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Dr. Cecilia Sorensen, the director of the Global Consortium on Climate and Health Education at Columbia University, agrees that outdoor workers are more at risk for heat-related issues on the job.

"So outdoor workers, agricultural workers, construction workers, and then we think about areas of the country where there's, you know, widespread environmental injustice issues related to neighborhoods," said Dr. Sorensen.

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One of those factors is tree canopy, which can lower street temperatures dramatically.

When ABC7 did an aerial survey for a previous report, we spotted stark differences in tree cover between higher and lower-income neighborhoods across the Bay Area.

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Vivek Shandas, professor of climate adaptation at Portland State University, studies the disparity.

"And so what we now know across the country in all the cities we study is that those historically segregated neighborhoods have orders of magnitude less tree canopy than they're invested in and greenline counterparts, and that legacy casts a long shadow. And we're now in the midst of trying to write some of those historical wrongs," said Shandas.

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Maintenance director Mike Will says expanding tree canopy is already a priority at Santa Clara County parks. Managers said they planted close to 600 trees last year and have ongoing planting goals over the next several years as well.

"Our goal now is to step up our tree planting process so that 15 years from now we have decent shade trees for the public for when they come to our park, they have a place to get out of the sun," said Will.