The first tropical threat of the season to the U.S. is set to impact Southern California, rather than the more typical East Coast or Gulf of Mexico.
Tropical Storm Hilary formed along Mexico’s western coast on Wednesday morning and is forecasted to bring significant rainfall to Southern California early next week. If Hilary makes landfall, it will be only the fourth storm of tropical storm strength or greater to do so in this region.
Hilary is expected to intensify over the next two to three days. According to the National Hurricane Center, the storm could reach peak intensity as a Category 3 hurricane with 120 mph winds by Saturday morning.
However, cooler ocean temperatures and potential interaction with Mexico’s Baja Peninsula are likely to weaken the storm shortly afterward. By Sunday, heavy rains are anticipated to reach Southern California and southwest Arizona.
Significant rainfall is expected in Southern California, with flash flooding risks early next week.Historically, no hurricane has ever moved into California. Only three tropical storms have previously reached the area: Nora in 1997, Kathleen in 1976, and the Long Beach storm in 1939.
Despite this, remnants of tropical storms and hurricanes have often brought tropical rain to Southern California and the Southwest. For instance, in 2022, Hurricane Kay caused a fatal debris flow in San Bernardino County.
The National Hurricane Center predicts that Hilary will transition from a tropical storm to an extratropical storm by Monday morning near the California-Mexico border, with maximum sustained winds of 60 mph.
Long-range models suggest potential wind gusts of 40-60 mph in Southern California on Monday, particularly in mountainous areas. However, the primary concern is the heavy rainfall rather than wind damage.
There is already a slight risk of flash flooding for early next week, which may escalate to moderate or high risk if the forecast continues to target Southern California.
The Weather Prediction Center forecasts rainfall totals of 2-4 inches, with isolated areas receiving over 6 inches—a significant amount for the typically dry Southwest.