October heat wave puts California's aging infrastructure to the test

An October heat wave continues to bake California, pushing temperatures well above average and putting schools, homes and other infrastructure to the test as the state grapples with extreme heat.

The heat wave is affecting parts of California and the Desert Southwest, with unusually high temperatures expected to continue through midweek. Temperatures across affected areas are running above average, with daytime highs reaching 32 to 40 C, according to the National Weather Service.

The National Weather Service said the heat has pushed HeatRisk levels to "Major" and "Extreme" — levels 3 and 4 on a four-tier scale.

In the San Francisco Bay Area, a heat advisory has been extended through Thursday night. Temperatures in inland valleys are expected to range from about 35 to 41 C, while some coastal communities will remain considerably cooler.

Parts of Southern California are also under extreme heat warnings, with temperatures in some inland areas expected to reach as high as 42 C.

The unusually hot start to October is drawing renewed attention to a challenge facing California, particularly in coastal communities where air conditioning has historically been less common.

For example, about 65 percent of homes in San Francisco County lacked air conditioning in 2023, while about one-quarter of homes in San Diego County had no air conditioning, according to estimates by the US Census Bureau.

The issue has become particularly visible on college campuses, where students at several University of California campuses have raised concerns about dormitories and other buildings without air conditioning during the latest stretch of hot weather.

At the University of California, Irvine, officials issued a high-heat advisory covering Oct 2 through Wednesday and opened several air-conditioned cooling centers.

Similar measures have been taken at the University of California, San Diego, where the university has directed students to air-conditioned "cool zones", while the school housing reads: "The Housing units do not include air conditioning. We rely on the mild temperature of La Jolla and our proximity to the ocean breeze to keep our units comfortable."

Students have also taken to social media to describe conditions inside their dormitories. Many California university buildings, particularly residence halls, were built without air conditioning. The latest heat wave has prompted students to describe difficulties sleeping and studying in rooms that remain hot well into the night.

"Our rooms have 3-6 fans in them, but they do nothing but push around hot air since the windows barely open. It has gotten up to 94 F (34 C) in our room sometimes, and the bathroom feels even worse," a student wrote on Reddit. "They (the school) won't let us have portable AC units either, which is insane. I'm so upset that this university cares more about maintaining its status as a 'green school' than the safety of the students."

The problem extends well beyond universities. In Oakland, where many public schools were built decades ago, the school district has been working to retrofit campuses for hotter conditions.

A district resolution this year said 81 percent of Oakland Unified School District campuses were built before the 1970s and about 2,100 classrooms lacked forced-air cooling. Some classrooms have reached 29 C, even when outdoor temperatures were lower, according to the district.

At some schools, parents have taken matters into their own hands, launching fundraising campaigns to pay for air-conditioning installations in classrooms.

The heat is also affecting Californians whose jobs keep them outdoors. The California Division of Occupational Safety and Health (Cal/OSHA) has also issued an advisory as high temperatures spread across the state. Construction workers, landscapers, delivery workers and agricultural workers can face particularly prolonged exposure to extreme heat.