Weather service warns of hypothermia risk as overnight temperatures plummet in SoCal

Weather whiplash continues in Los Angeles County, where after weeks of dangerously warm and windy conditions, followed by sudden rainfall and small mudslides, the National Weather Service has issued a warning for a new threat — cold overnight temperatures that could pose a risk of hypothermia.

Temperatures in the county will plummet to the 30s and 40s on Tuesday and Wednesday nights, with daytime highs in the 50s and low 60s, as the low pressure system that brought weekend rains continues to spin through the region, according to the weather service. Temperatures as low as the mid 20s are forecast in the Antelope Valley.

Meteorologists warn that, with these cold temperatures, there’s a risk of hypothermia for people and animals, and sensitive plants and crops could be damaged.

The number of hypothermia deaths in California has grown in recent years. In 2023, 166 Californians died from hypothermia, double the number in 2015, according to data from the U.S. Centers for Disease Control and Prevention.

Experts attribute this uptick to the increase in people living on the streets; homeless people are at the highest risk of developing hypothermia, a condition that can set in at air temperatures as high as 50 degrees.

This cold snap will also affect areas of the interior Central Coast, San Joaquin Valley, Ojai Valley and Santa Barbara County, where the weather service has issued freeze alerts.

A gradual warmup will begin Friday as a ridge of high pressure moves into Southern California, but temperatures will remain several degrees below normal in L.A. County, according to the weather service. The warming is expected to continue through the weekend, with highs in the mid 70s predicted for the San Fernando Valley and in the 60s to low 70s elsewhere.

Meteorologists say there’s a good chance of widespread rain in L.A. County next Tuesday and Wednesday and predict that this will be a heavier rainfall than the splatter over the weekend.

“Rain rates and totals could be quite a bit higher,” said the weather service. “Certainly something to pay close attention to, especially for those near recent burn scars.”

Landslides are a risk after wildfires because the heat of the fire makes the soil repellent to water. When rainfall intensity is high — more than half an inch per hour — water can start flowing on the surface downhill instead of percolating below ground, and can begin to pick up rocks and debris.

The weekend rainfall led to minor slides and flooding in the Palisades burn area, prompting the temporary closure of Topanga Canyon Boulevard. The 14,000-acre burn scar from the Eaton fire is also an area of concern.