SAN FRANCISCO (KRON) — Hurricane Hilary grew rapidly to Category 4 strength off Mexico’s Pacific coast on Friday and could reach Southern California as the first tropical storm there in 84 years, causing “significant and rare impacts,” including flooding.

“All eyes are on the Pacific as Hurricane Hilary strengthened today to a Category 4 storm,” said KRON4 Meteorologist Kyla Grogan. “This system is expected to undergo rapid intensification and strengthen to a major hurricane over the next 24 hours.” 

The U.S. National Hurricane Center said a tropical storm watch has been issued for Southern California, for the first time ever.

“Hurricane Hilary will threaten the coastal communities of the Baja California Peninsula as it comes ashore, likely as a CAT2 or CAT3 system,” Grogan added.

Graphic: Kyla Grogan

Hilary had sustained winds near 145 mph early Friday, and was expected to strengthen a bit more before starting to weaken. It nevertheless was expected to still be a hurricane when approaching Mexico’s Baja California peninsula on Saturday night, and a tropical storm when approaching Southern California on Sunday.

“The structure of Hurricane Hilary is very impressive, but it will be moving into cooler waters as it heads north which will help inhibit its development a bit,” she explained. “Once it encounters land, it is projected to cause areas of flash flooding and landslides over Baja California from Friday into Sunday. Then the remnants of Hilary will continue into the Southwestern United States including parts of California later this weekend and into next week.”

No tropical storm has made landfall in Southern California since Sept. 25, 1939, according to the National Weather Service.

Hurricane Hilary’s Northern California impact

While Hilary is expected to bring rain and potential flooding to Southern California, according to Grogan, the Bay Area is expected to only see remnants of the storm.

“As far as any rain reaching the Bay Area, right now models are steering it a bit more to the east and that would only leave us with a slight chance of receiving minimal rain,” she explained. “But certainly, we can expect to see our cloud cover increase and our humidity levels rise as this moisture moves into the state and causes atmospheric instability.”

While Friday is expected to remain dry across the Bay Area, Grogan says the weekend could see a shift with the possibility of rainfall early next week.

Graphic: Kyla Grogan

“As we get closer to the weekend the forecast models should start to show more clarity, so this is one to keep an eye on,” she explained. “Any Bay Area impacts would likely be next Monday into Tuesday. Stay tuned.”

The Associated Press contributed to this report.