CHICAGO (CBS) -- A dangerous heat wave has more than half of the country sweltering this weekend.
Temperatures near -- and above -- 100 degrees are combining with thick humidity to present serious health hazards.
The National Weather Service posted a reminder Friday that heat kills more people each year than tornadoes, lightning and floods.
"Safety is everyone's responsibility, so we remind everyone to stay hydrated and check on our neighbors and family," said Rich Guidice of the Office of Emergency Management and Communications in Chicago.
Thermometer readings are in the 90s across the Midwest, but as any dog knows, when you add in the humidity it feels like 105 or even 110 degrees. Overnight, lows in the 80s won't cool down anything.
Eighteen states from New Mexico to Michigan have issued heat advisories, warnings or watches, making up a heat dome that is descending on 60 million people.
A storm knocked out power to 30,000 people in St. Louis, meaning they lack air conditioning.
The heat index is in triple digits in Kansas City, Des Moines and even Minnesota, where the Minneapolis Star Tribune said the state is like "Saudi Arabia with lakes."
Denver's temperature on Thursday was a record-tying 105.
As the scorcher expands east, New York will bake this weekend and so will Vermont up to the border with Canada.