Where are the ‘heat islands’ in Sonoma Valley?

Urbanized and industrial areas often retain more heat than rural areas. New geographic data show the hot spots of Sonoma Valley.|

Warmer temperatures can be expected as June begins, but some Valley neighborhoods will be feeling the heat more than others.

Geographic data from the Trust for Public Land provides a detailed view of the “heat islands” in Sonoma Valley — specifically, the west side in the city of Sonoma and numerous places in the Springs — caused by denser urban infrastructure and a lack of tree cover.

“Just visually, if you if you look at Sonoma’s east side, it’s like ‘Leave It to Beaver.’ It’s shade line streets who wouldn't want to live in a nice place like that?” said Fred Allebach, a Valley resident and member of the Sonoma County Equity Working Committee. “The places that are denser and have more multifamily housing have less of that. Look at Fetters Apartments … there's barely any trees in that parking lot at all.”

The “heat island effect” occurs as urbanized or industrial areas experience higher temperatures than outlying areas, leading to “higher daytime temperatures, reduced nighttime cooling and higher air-pollution levels,” according to the Environmental Protection Agency. Daytime temperatures in urban areas can range from 1 to 7 degrees higher than temperatures in outlying areas, and nighttime temperatures can be 2 to 5 degrees hotter.

Neal Ramus , director of community engagement and education at the Sonoma Land Trust, said the disproportionately hot areas of Sonoma Valley are located where there is more concrete and asphalt with fewer trees.

“Urbanization does a bunch of things for temperature,” Ramus said. “There’s often less vegetation, there’s less trees that block the sun. There’s even research that shows that black asphalt on roads increases temperatures.”

Heat islands are typically centralized in cities, but the same effect can take shape in more rural areas like Sonoma Valley where there is less tree cover and more uncovered concrete.

Climate change and “the heat island effect“

In Sonoma Valley, the inequity in natural infrastructure like trees is starkly obvious.

“There's far less heat islands to the east of Broadway. And if you look on Google Maps … you can see the trees, you can literally see trees, every other house, there's big old trees,” Ramus said. “Then you look on the west side of Broadway toward the hospital. There’s a lot of mobile home parks, there's a lot more apartments, there's no trees. Like you can you can actually see it. And that's where all the heat islands are.”

These divisions represent the historically inequitable investment of resources in neighborhoods across the Valley, Ramus said, as the east side was given park-like green space when it was built, a luxury not provided in all neighborhoods.

In Sonoma Valley, heat islands are most common in lower-income communities, particularly in Boyes Hot Springs, Fetters Hot Springs, Agua Caliente and the western half of the city of Sonoma.

While about 25% of residents on Sonoma’s west side are considered low-income, that number jumps to 40% to 50% in the Springs, according to data from the Trust for Public Lands. Allebach noted that a neighborhood on the western side of Highway 12, from Verano Avenue to Madrone Road, has the highest rate of poverty in the Valley.

Lower-income communities have more affordable housing like manufactured homes, which can lack the insulation needed to stop heat from coming indoors, Allebach said.

Those who live in heat islands may be less equipped to cope with their negative impacts. “People living under the poverty level or at high risk of falling into poverty may not be able to afford air conditioning or transit to cooling centers,” according to a 2014 report by the Sonoma County Transportation Agency on climate change.

With worsening heat waves expected in coming years, experts say it’ll be important to create more adaptable environments.

“Heat is one of the impacts of climate change,” Ramus said. “We can't fix it all just with trees. But it's more of an illustration of how inequitable resources and communities have continued to disproportionately impact marginalized communities.”

Contact Chase Hunter at chase.hunter@sonomanews.com and follow @Chase_HunterB on Twitter.

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