Southern California experiences unusually warm nights and coastal heat despite typical daytime temperatures

Temperatures across Southern California have been close to seasonal averages during the day, but nighttime lows remain unusually high, according to the National Weather Service and climate researchers. Climate scientist Daniel Swain described the summer as “extraordinarily, arguably record-breakingly, warm at night,” while noting that daytime highs have not been extreme.

The National Weather Service predicts the region will face its hottest week of the year, with daily maximums in Los Angeles, Long Beach, Santa Monica and Burbank expected to approach record levels. The trend mirrors a broader global heat wave, with July 2024 tying the warmest on record since 1850, according to NOAA data.

Swain explained that the persistent warmth is linked to a marine heat wave that has raised near-shore ocean temperatures, setting a higher baseline for nighttime cooling along the coast. Elevated sea surface temperatures also increase humidity; dew points have frequently reached the low 70s Fahrenheit, comparable to conditions in Miami.

Higher nighttime temperatures can impede the body’s recovery from daytime heat, raising the risk of heat-related illness and placing additional stress on ecosystems and infrastructure. Researchers note that many U.S. regions are seeing overnight temperatures rise faster than daytime highs, a pattern associated with climate change.

Local residents have reported increased reliance on air conditioning and discomfort during evenings. In Long Beach, a power outage affecting over 22,000 customers compounded the heat, leaving residents without fans and prompting some to seek cooler shelter elsewhere.

Experts anticipate that the ongoing El Niño pattern will sustain the warm, humid conditions through the fall and possibly into early winter, with nighttime temperatures remaining elevated.