According to a 2024 report analyzing the costs and benefits of San Diego County’s Climate Action Plan (CAP), residents in the region are now experiencing six dangerously hot days each year compared to just three in the years between 1950 and 2005.The threat of excessive heat in the region is projected to increase with time. Due to weather patterns fueled by climate change, the county said it could face 17 of those days by 2053.That’s costing San Diegans in more ways than one.
Extreme heat is defined as temperatures that are much hotter and/or more humid than average for a particular location and the time of year.It’s now the leading cause of weather-related deaths in the U.S., according to the National Weather Service. And in the Southwestern corner of the country, San Diego County is no stranger to extreme heat. The analysis of the county’s CAP said heat is the most prevalent climate risk in San Diego — ahead of flooding or wildfire.“We see more days above certain thresholds each year. We see longer duration of heat waves, we see warmer nighttime temperatures, which is really important for health impacts,” said Scripps Institution of Oceanography economist Tom Corringham. “If the temperatures are hot at night or humid at night, there’s less time for the body to recover.”His research focuses on understanding the economic impacts of climate change and extreme weather events.
Scripps Institution of Oceanography research economist Tom Corringham stands outside of Nierenberg Hall at the Scripps Institution of Oceanography campus, July 20, 2026.
Corringham said the largest impacts of extreme heat are increased emergency services and health care visits due to heat illness. The major impacts also include increased energy demand and costs as people try to cool down businesses and homes with air conditioning.“Extreme heat tends to affect our more vulnerable members of our communities — older people, children, folks with pre-existing conditions tend to be hit hardest,” he said.Then there are the trickle-down costs of extreme heat. Those include impacts on worker safety and productivity, impacts on agriculture, infrastructure and other businesses.“When it comes to something like heat, it’s invisible. It’s not something that is easy to quantify, that is easy to measure. But we know it has an impact, and it affects all of us in a quiet way,” Corringham said.School impactsExtreme heat has significant impacts on kids.“School performance tends to go down with extreme temperatures, especially in classrooms that don’t have air conditioning or a way of cooling the space,” Corringham said.Dr. Vi Nguyen is a full-time pediatrician in Otay Mesa. She’s also co-chair of San Diego’s American Academy of Pediatrics Climate Change and Health Committee.Nguyen said she is treating more patients due to heat illness in recent years.
A fan inside a classroom at Rancho Bernardo High School circulates the air as the Poway Unified School District tries to fix the broken air conditioning system at the school.
“As a community pediatrician, I see more kids come in for heat-related illnesses, whether that be dizziness and feeling dehydrated, but also just thermal burns,” Nguyen said.The impacts at schools can be deadly too. A young boy died in Riverside County at a Lake Elsinore middle school, prompting statewide policy change.“In August of 2023, Yahushua Robinson, a 12-year-old, and his entire middle school class was made to do PE during an excessive heat week. He unfortunately collapsed and died,” said family advocate Christina Christopher Laster.Beginning July 1 of this year, Senate Bill 1248 took effect. It’s a result of Robinson’s death. It mandates all public and charter schools to have a written, enforceable weather safety policy to protect students from heat-related risks.San Diego County Office of Education data show five school districts in the region begin the calendar school year this month.Sticker shockAccording to a 2024 California Department of Insurance report, seven major heat events between 2013 and 2022 caused an estimated $7.7 billion overall in damages and losses across the state.The events led to nearly 460 premature deaths, more than 5,000 hospitalizations, roughly 10,600 emergency department visits and more than 138,000 outpatient visits, according to the report.The total social welfare losses associated with premature death from the extreme heat events range from $77 million to $2.2 billion per event.That doesn’t include the out-of-pocket expenses that patients are responsible for in nonfatal medical visits. Those numbers add up to more than $47.5 million across all extreme heat events in the outpatient setting alone.The extreme heat waves also led to an estimated $580 million in combined damages across the seven events due to power outages. Three of the events impacted San Diego County.The breakdownAs a general rule of thumb, temperatures are higher further inland. And communities with less access to air conditioning experience more hospitalizations from extreme heat. But this doesn’t affect everyone equally.“Just having air conditioning alone isn’t enough. A lot of people, it’s reported that they have air conditioning, but chose not to use it during these heat events just to save money, and that can be dangerous as well,” Corringham said.The county report said the health and financial costs of extreme heat are more burdensome for low-income communities, people of color and people experiencing homelessness. That’s because families in these households are generally less able to afford air conditioning and operating expenses, and/or they tend to live in hotter areas.
A window air conditioning unit is set up at a home in San Diego County, July 21, 2026.
Additionally, it’s estimated that there are 220,000 San Diegans employed in heat-exposed industries, like construction, manufacturing, transportation and agriculture. Each time there’s an extreme heat day, experts said there are at least 41 minutes of lost work time for people in those industries.Extreme heat affects more than people; it takes a toll on infrastructure too.“There are costs to transportation networks. Rail can buckle, there can be damage to our road networks, and electric substations can be damaged,” Corringham said.By the numbersOn average, 194 heat-related injuries and illnesses send people to the emergency room in the county every year.New census data show nearly 26% of San Diego County homes don’t have air-conditioning, which can lead to negative health outcomes.The cost of air conditioning can vary greatly depending upon the size of a home and whether the goal is to cool a single room or the whole space. Some window and portable units cost a few hundred dollars. But getting full home, central air conditioning can cost from the low thousands to over $20,000 if there’s no existing ductwork.Then there are the monthly costs of running the units. The smaller room-specific window and portable units may cost less than $100 per month if used wisely. Central AC in an inland community could easily push into the mid-hundreds of dollars per month for a full house.“At the household level, folks typically spend a little under $200 a month on electricity. That can go up 10%-20% during a heatwave. So it does affect people’s pocketbook(s),” Corringham said. “For people that can’t afford air conditioning, I mean that’s the real danger zone.”What can be doneAt the public level:Urban heat islands are hotter than normal areas with dense concentrations of pavement, buildings, and other infrastructure. Planting and providing tree canopy is one of the most effective methods to provide some relief.“In highly developed areas, temperatures are even higher than in more rural areas. So if you’re able to increase the urban forest, the urban tree canopy, that also brings temperatures down,” Corringham said.Providing shade structures at places like bus stops also helps provide some relief, Corringham said. Some cities are also installing “cool pavements,” which are specially designed or treated surfaces that reflect more sunlight and absorb less heat than traditional paving materials.
Trees and a health urban forest may be the best solution to urban heat islands. Aug 6, 2024
San Diego’s Climate Action Plan said the city aims to install the cool pavements in parking lots and in the public right-of-way.At the personal level:There are also now ways to track who in the county faces the most heat risk and why that is with the new San Diego Heat Risk Explorer.Knowledge is power! Familiarize yourself with the tool to understand your neighborhood and other places in the county.In San Diego County, there are nearly 80 Cool Zone locations, at places like libraries and senior centers, where residents can cool off in air-conditioned spaces for free. People who need a free ride to the site can call 211.How are locals adapting:Those eligible can take advantage of weatherization programs for low-income households. Those are government and utility-funded initiatives that provide free or low-cost energy-efficiency upgrades to homes.As for people considering a roof replacement sometime soon, Corringham said to consider installing a “cool roof,” which helps reflect the sun’s rays. Other ways to improve energy efficiency include adding better insulation, energy-efficient windows, and solar panels for those trying to cut down on their long-term energy costs.“At the personal level, I think the most important things are: stay hydrated, avoid hard labor or excessive effort during the hottest parts of the day, don’t leave children or pets in a car, and use the air conditioning if you have it, or a fan,” Corringham said. “Keep the blinds closed during the day.”
Window air conditioning units hang outside of Nierenberg Hall at the Scripps Institution of Oceanography campus, July 20, 2026.
When it comes to air conditioning, it can be expensive. For those who aren’t able to afford central AC, Corringham said there are benefits to getting a smaller unit for a single room.“If you don’t have air conditioning, you don’t have central HVAC, but you’re able to put in a unit for a single room, for your bedroom for example to cool things down at night — fantastic adaptation. I would certainly recommend doing that if it’s possible,” he said.For those without air conditioning in any form, or who can’t afford to use it, a heat researcher offered these general tips to NPR:Carry a water bottle and drink plenty of fluids. It doesn’t have to be just water.Cool off with a cold shower or by splashing water on your face and hands.Cover your head or neck with a white wet towel.Avoid going outside during the hottest parts of the day.The County of San Diego said to watch out for signs of heat exhaustion, including: paleness, dizziness, headache, tiredness, weakness, muscle cramps, excessive sweating, nausea or vomiting and fainting.For people feeling those symptoms, it said to move to a cool place; loosen your clothes; put cool, wet clothes on your body or take a cool bath, and to sip water. The county said to get medical help right away if you are vomiting, your symptoms get worse or last longer than an hour.It also says to check in on neighbors, family, or friends who are at increased risk, especially if they live alone.What’s next?Corringham said the entire world is feeling the effects of global warming. He said some in San Diego County are lucky they have a beachfront location. But much like how extreme heat affects neighborhoods and people differently, not everyone is so fortunate to access the Pacific Ocean.“The ocean modulates the temperature to some extent, at least in the coastal parts of San Diego. We also have the inland valleys and inland deserts which can get very hot,” he said.Corringham also said extreme heat doesn’t exist in a bubble.“Extreme heat is one of the primary drivers of wildfire and drought. And the cost of wildfire and drought are very high and very meaningful in California,” he said.While the climate is changing and there are ways we can adapt, he said ultimately “Intervention number one is moving away from fossil fuels and towards a green economy.”
San Diego’s cost of living is roughly 50% higher than the national average. While the median household income is around $104,321, the income needed to afford a median-priced home ($920k+) is now estimated at over $260,000.
