Life-threatening heat is baking 14 states from Arizona to Texas to Florida.
In the West, temperatures on Friday are forecast to reach 110 degrees in Redding, California, and 116 degrees in Phoenix and Palm Springs, California.
MORE: Heat stroke vs. heat exhaustion: Extreme heat safety tipsAll-time records could be broken in the Southwest this weekend.
In Phoenix, where temperatures have been above 110 degrees for 14 days in a row, the heat is forecast to soar to a scorching 119 degrees this weekend.
Las Vegas is expected to reach its all-time high temperature of 117 degrees on Sunday.
MORE: How does extreme heat affect mental health?Death Valley, California, could hit 130 degrees, nearing its hottest temperature on record -- 134 degrees -- which was set in 1913.
The West's extreme heat is spreading this weekend with heat alerts expanding to the Pacific Northwest.
MORE: How to conserve energy during a heat waveThis heat wave will likely peak on Sunday for much of the region and may continue into next week in some areas.
The Southeast is also enduring a dangerous heat wave.
On Friday, the heat index -- what the temperature feels like with humidity -- is forecast to hit 108 degrees in Dallas, San Antonio and New Orleans; 110 degrees in Jackson, Mississippi; and 105 in Charleston, South Carolina.
In Miami, where it'll feel like 102 degrees on Friday, the heat index has climbed over 100 degrees for 33 straight days.
Click here for tips on how to stay safe in the heat.