Tropical Storm Marie could bring rain and surf to Southern California this weekend

Meteorologists are monitoring Tropical Storm Marie, which is expected to strengthen into a hurricane before weakening as it moves northward toward Southern California. The National Weather Service in San Diego said the storm’s track remains uncertain, but a northward path could bring rain and surf to the region over the Labor Day weekend.

UC climate scientist Daniel Swain noted that even if the system reaches the area, it is likely to be below hurricane strength, describing a “decaying tropical storm” that could deliver “tons of moisture, hefty showers and thunderstorms” along with dangerous coastal waves. Meteorologist Sebastian Westerink of the San Diego office added that wind impacts are expected to be modest, comparable to a strong winter storm.

Coastal flooding is a primary concern, especially as the storm-generated swells coincide with some of the month’s highest tides. “There’s increasing confidence in moderate-to-large surf from the south swell starting as early as Friday. We could have coastal flooding because we’ll have above-normal tides during the same time,” said Kristan Lund, a meteorologist with the Oxnard weather service office.

While the likelihood of widespread heavy rain is low, any significant rainfall in mountainous areas could trigger flash floods, landslides or debris flows, Swain warned. The scenario is reminiscent of the 2023 remnants of Hurricane Hilary, which produced post-tropical flooding across the region.

Experts note that the current El Niño development may intensify storm activity later in the year, potentially increasing the risk of similar events. However, Westerink emphasized that the cooler ocean temperatures off Southern California—generally in the high 60s to low 70s Fahrenheit—remain below the threshold needed to sustain a full-strength hurricane.

Historical records show only two tropical-storm-strength systems have crossed California, in 1939 and 1997, both causing limited damage. Researchers caution that climate change could make heavy, tropical-origin rainfall more common in the future.