May 20, 2024 - News

Extreme heat is San Diego's most prevalent climate risk

Illustration of the San Diego skyline under a hot sun.

Illustration: Brendan Lynch/Axios

Extreme heat is the most widespread climate risk in San Diego, and its frequency will increase substantially in most of the city over the next 30 years, according to a new Brookings report.

Why it matters: Acute climate events like hurricanes and wildfires get more media attention, but chronic ones like extreme heat can have the potential to impact more people — and low-income households need more support to adapt.

The big picture: Inland neighborhoods unsurprisingly experience more extreme-heat events — days with temperatures above 90 degrees — than coastal areas, but more San Diegans are expected to feel the heat in coming years.

  • 20% of neighborhoods last year experienced 6-20 high-heat days last year. The Brookings report says that percentage could swell to 52% over the next three decades.
  • Neighborhoods with more than 20 days above 90 degrees may go from 12% last year to 21% in 30 years.
  • Meanwhile, the 32% of neighborhoods that felt extreme heat two or fewer times last year is expected to fall to just 1%.

Threat level: The median annual cooling cost citywide is $505, and a key question facing city leaders is what share of households will struggle to cover those costs as prolonged heatwaves and extreme-heat days increase.

  • "Unfortunately, that question is difficult to answer consistently across neighborhoods with the available data," the report's authors write.

The intrigue: The authors were surprised to find that, unlike in other cities, heat risk is not strongly correlated with race or income in San Diego.

  • That's in part because some low-income neighborhoods — like Barrio Logan — are near the coast, while some wealthy neighborhoods — like Scripps Ranch — are inland.

Zoom in: The study isolated City Heights, where extreme-heat risks and cooling costs can vary from one part of the community to another.

  • High-heat days are more common on the east side of the neighborhood, and heating costs are higher on the northern edge.
  • City Heights' median annual cooling cost of $574 is 15% above the citywide average, while the community's typical household income of $47,299 is less than half the city's.
  • In one 12-block City Heights area, zero properties experienced more than 20 high-heat days last year, yet 209 properties in that area are expected to do so in 30 years.

The bottom line: "The challenge of how to keep people safe and healthy — as both population and housing stock continue to age — will only become more urgent," the study authors write.

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