The word "scorch" likely originated in Middle English, possibly from a Scandinavian source related to the Old Norse word "skorpna," meaning "to shrink" or "be shriveled".   It possibly blended with the word "torch". The word "scorch" means to burn superficially, or slightly, but enough to change the color or texture of something. 

The adjective "scorching" was first used in English in the mid-1500s, specifically 1563.  The word is formed within English, derived from the verb "scorch". 

Examples of "scorching" used in a sentence: 
"It was scorching hot inside the greenhouse. 
"We're due for another scorching summer day." 
"The sun was high in the sky, its rays reaching down and scorching the Earth." 
"The bright suns rays touched her sneakers, scorching them with fiery heat."
"It was about eleven o'clock in the morning -- scorching hot, dusty." 
"He swung himself off the lounger with as much grace as he could muster and stepped gingerly on to the scorching bricks."

Just the facts:

SCORCH Definition & Meaning - Merriam-Webster

SCORCHING Synonyms: 129 Similar and Opposite Words | Merriam-Webster Thesaurus