The extreme heat that has been confined to the Northwest and South is now expanding into the central U.S., setting up a hot weekend ahead for most of the country.  

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

Scattered thunderstorms are in the forecast for the Great Lakes, East Coast, Gulf Coast, Florida and the Southwest on Thursday.  

Heat expands across the country on Thursday

High temperatures across the country on Thursday. (Credit: Fox News)

Meanwhile, Tropical Storm Hilary is churning out in the Pacific and is expected to intensify rapidly off the Coast of Mexico. 

Tropical Storm Hilary forecast track

Tropical Storm Hilary's forecast track. (Credit: Fox News)

Hilary is anticipated to impact southern California on Sunday and Monday, bringing extremely heavy rain, strong winds and some tornadoes as the system moves onshore.  

Tropical Storm Hilary on Sunday

Tropical Storm Hilary's track on Sunday. (Credit: Fox News)

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Rain forecast in southern California

Rain forecast in southern California from Saturday through Wednesday. (Credit: Fox News)

This will be a very big deal for some of the desert areas, where flash flooding and mudslides are likely.