(USA TODAY) - The USA is closing in on its hottest month in recorded history.
With five days to go in July, preliminary data show that the heat could top records set decades ago: "The warmest July for the contiguous U.S. was in 1936, when the nationally averaged temperature was 77.43 degrees, 3.14 degrees above average," says climate scientist Jake Crouch of the National Climatic Data Center.
Preliminary data from the center show the national temperature for the first three weeks of July was 3.63 degrees above average. If the heat continues, and after the data are more closely analyzed, that would top July 1936.
Five cities - Chicago, St. Louis, Detroit, Indianapolis and Denver - are all on pace to shatter their all-time monthly heat records.
"It's hotter here than it is in Arizona," complained Mary Dominis in Chicago earlier this month, who was visiting the Windy City from Tempe.
St. Louis is seeing some unbelievable heat this summer: On Wednesday, the city hit 108 degrees, says Weather Underground meteorologist Jeff Masters. "This marked the 11th day this summer in St. Louis with temperatures of at least 105 degrees," he says, "beating the old record of 10 such days in 1934."
There was some relief in St. Louis on Thursday: the temperature didn't break 100.
Twenty-four people have died from the heat in St. Louis so far this summer.
Through Monday, there have been 3,740 record daily high temperatures set across the nation this month, compared with only 211 record lows, Weather Channel meteorologist Guy Walton says.
It's been unusually hot even in torrid Death Valley, Calif. On July 12 the low temperature at Death Valley dropped to just 107 degrees after hitting a high of 128 degrees the previous day, Masters says. Not only did the morning low temperature tie a record for the world's warmest low temperature ever recorded, the average temperature of 117.5 degrees was the world's warmest 24-hour temperature on record.
The Climate Prediction Center is forecasting more "excessive heat" in Nebraska, Kansas, Oklahoma, Missouri and Arkansas over the weekend and into early next week.