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Extreme heat: Here's what to know about Ventura County's increasing risk of hot days

Ventura County Star logo Ventura County Star 8/15/2022 Cheri Carlson, Ventura County Star
This map shows an increasing number of hot days in communities nationwide in 2053. © Courtesy of First Street Foundation This map shows an increasing number of hot days in communities nationwide in 2053.

The risk of extreme heat is rising in communities nationwide, more than doubling the number of hot days expected in Ventura County over the next 30 years.

That’s according to a new analysis released Monday by the First Street Foundation, a New York-based nonprofit that also has examined the risk of floods and wildfires for U.S. homes. The heat model is expected to help property owners and communities better understand their risk to extreme heat now and over the next 30 years.

“We hope people understand the exposure to extreme heat isn’t something that is just affecting them today but is something that’s going to continue to affect them into the future,” said Jeremy Porter, the foundation's chief research officer.

Researchers calculated the “feels like” temperature and identified the seven hottest days expected this year and how that number would increase by 2053 with the changing climate. They also examined exposure to dangerously high temperatures and the likelihood of three or more consecutive hot days or heatwaves. 

“The heatwaves that you’ve been exposed to are unbearable for some people. They’re relentless,” Porter said. "These are going to get worse."

Rising temperatures are going to continue to increase the exposure these events, he said.

Among the findings:

  • Nationwide, local hot days – when the temperature reaches that of an area's seven hottest days – will more than double by 2053. Miami-Dade County is expected to see the biggest shift, jumping from seven days at 103 degrees in 2023 to 34 days at the same temperature in 2053.
  • The western U.S. has the highest probability of experiencing heatwaves, which have been tied directly to disproportionate levels of heat fatigue, stroke and death.
  • As temperatures rise, most properties also will see an increase in electricity costs of air conditioning. In California, those costs are expected to increase by $574 million by 2053.

The report also found an "Extreme Heat Belt" emerging in the middle of the country that will expose millions to temperatures as high as 125 degrees.

In 2023, roughly 50 counties or 8.1 million residents are expected to experience those temperatures, according to the report. In 30 years, that number balloons to 1,023 counties or more than 107 million residents from Texas to Illinois.

“It’s no longer just a spattering of counties, but it’s this huge area across the middle of the country that reaches all the way up into southern Wisconsin,” Porter said.

More: State denies additional water for fire-prone Southern California neighborhoods

A deadly disaster

In Ventura County, the likelihood of a heatwave rises from 55% to 88% in 30 years, the researchers say. 

The county also will see an increasing number of local hot days. On average, the number is expected to more than double to 17 days at 93 degrees by 2053. That's up from seven days at the same temperature this year.

But temperatures vary city by city.

  • The number of days with a "feels like" temperature over 100 degrees in Simi Valley is expected to increase from seven to 19 by 2053. Days with a temperature over 90 degrees in the city is expected to jump from 63 to 83 in 30 years.
  • Santa Paula is expected to experience 17 days at temperatures at or above 94 degrees, up from seven days at that temperature this year.
  • Meanwhile, near the coast, Oxnard is expected to have 16 days at 85 degrees in 2053. That's up from seven days at that temperature expected this year.

Heat kills more people than any other climate-related disaster, said Dr. Gina Solomon, a principal investigator at the Public Health Institute in Oakland.

“We hear a lot about hurricanes and other weather disasters,” she said. “Even the direct effects of wildfires don’t injure and kill as many people as health effects from heat.”

But the temperature alone doesn't always predict danger. Part of what matters is how temperatures compare to what people are used to experiencing, according to Solomon.

While inland areas tend to be the hottest, research has shown a disproportionate jump in emergency room visits and hospitalizations in California's coastal communities during heatwaves. 

One reason may be the lack of air conditioning in coastal communities. But, also, in a coastal area, bodies are less likely to acclimate and people tend to get sicker during a heatwave.

“People in coastal counties may assume that heat doesn’t apply to them," Solomon said. "Then, it actually hits them hard when it does hit."

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'No escape'

Communities with fewer resources generally get hit much harder, said Lucas Zucker, policy director at the Central Coast Alliance United for a Sustainable Economy or CAUSE.

Tree-lined neighborhoods with air-conditioned homes and pools experience the heat differently than those living in areas with more concrete, smaller apartments and no air conditioning, he said. Many also work outside, including on construction sites and farm fields.

For those whose jobs require them to be outside, "there's really no escape," Zucker said.

Take a look: Ventura County's city-by-city guide to water-use restrictions amid California drought

In the early 1950s, three consecutive days of 95-degree heat rarely happened in the Los Angeles region, climatologist William Patzert said.

"As we got into the '80s, '90s, and the new millennium, we found the three-day heatwave was turning into seven-, eight-, nine-day heatwaves," said Patzert, formerly at NASA's Jet Propulsion Laboratory in Pasadena.

They were becoming longer, more frequent, and more intense, he said.

An increasingly urban landscape and warming caused by rising levels of greenhouse gasses were to blame, Patzert said. Large urban areas with more concrete, black roofs and less shade tend to collect heat during the day and retain that heat at night.

The First Street analysis used a combination of factors to calculate risk for individual properties, including the type of ground cover, the density of shade trees, and proximity to water. For example, a home will experience hotter temperatures in the middle of the street than one next to a park.

“We can actually see at very hyperlocal, very small scales what the temperature variations are,” Porter said. "The model will allow you to pick up those types of things."

To read the report or find out how heat is expected to affect your home, go to

Cheri Carlson covers the environment for the Ventura County Star. Reach her at or 805-437-0260.

This article originally appeared on Ventura County Star: Extreme heat: Here's what to know about Ventura County's increasing risk of hot days


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