“Hotter than a firecracker on the Fourth of July” (very hot)

Entry in progress—BP
 
“Hotter than noon on the Fourth of July” and “Hotter than the Fourth of July” are related sayings.
 
Newspapers.com
 
Newspapers.com
3 July 2009, The Daily Oklahoman (Oklahoma City, OK), “Some cool statistics sparked by the Fourth” by Bryan Painter, pg. 16A, col. 1:
You’ve probably heard them for years, the Fourth of July cliches.
 
“Hotter than a firecracker on the Fourth of July.” “Hotter than noon on the Fourth of July.” And the generic “Hotter than the Fourth of July.”