Hurricane Hilary, which is bound to impact California and the Southwest, is "strengthening rapidly" Thursday and is "likely to become a major hurricane" by the end of the day, forecasters are warning. 

As of midday Thursday, the storm, which has now been upgraded to a Category 2 hurricane, is centered about 500 miles south-southeast of Cabo San Lucas in Mexico, with current maximum sustained winds of 105 mph, according to the National Hurricane Center (NHC). 

"Heavy rainfall in association with Hilary is expected to impact the Southwestern United States from Friday through early next week, peaking on Sunday and Monday," the NHC said in its latest advisory.  

"Rainfall amounts of 2 to 4 inches, with isolated amounts in excess of 8 inches, will be possible across portions of southern California and southern Nevada," it added. 

‘SIGNIFICANT’ IMPACTS EXPECTED FROM HURRICANE HILARY IN CALIFORNIA, SOUTHWEST 

Hurricane Hilary track

The current track of Hurricane Hilary. (FOX Weather)

FOX Weather is forecasting parts of Arizona and Utah to be hit with several inches of rain as well through next Wednesday. 

The network, citing the NHC, reported that rapid intensification occurs when a tropical cyclone’s maximum sustained winds increase by at least 35 mph over a 24-hour period. 

"Maximum sustained winds have increased to near 85 mph with higher gusts. Rapid strengthening is forecast during the next day or so, and Hilary could become a major hurricane later today," according to the NHC. 

Forecasters say "hurricane-force" winds from the storm are already extending outward up to 70 miles from its center. 

STORM CHASER WORKS TO BUILD A HOUSE THAT CAN WITHSTAND CATEGORY-FIVE HURRICANE WINDS 

Hurricane Hilary forecast rain totals

Expected rainfall totals through next Wednesday from Hurricane Hilary. (FOX Weather)

In Mexico, the government "has issued a Tropical Storm Warning for the southern portion of Baja California Sur from Cabo San Lazaro southward on the west coast and Los Barriles southward on the east coast," while a "Tropical Storm Watch has been issued north of Cabo San Lazaro to Puerto San Andresito on the west coast," the NHC said. 

The NHC also said, "Large swells generated by Hilary will affect portions of the coast of southwestern Mexico and the Baja California peninsula over the next few days."  

Hurricane Hilary flood threat

The forecast flood threat from Hurricane Hilary. (Fox Weather)

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"These swells are likely to cause life-threatening surf and rip current conditions," it added.