The 'heat' theme

Has anyone ever explained the recurring "heat" theme in this film?

Examples: When Victoria is walking back to her hotel after the audition at Chez Lui, there are a number of posters and handbills posted on walls and kiosks that she passes that reference heating ("chauffage").

Also, as King Marchand is sneaking out of Victoria and Toddy's suite after spying on Victoria in the bath, as he's crawling past the bed, Toddy is reading a magazine article entitled "Quand on meurt de chaleur," or "When you're dying from the heat."