Wiktionary
a. (context idiomatic English) extremely hot (having a high temperature: of an object, the weather, a living creature)
Usage examples of "boiling hot".
From Hartman's Family Physitian, 1696: 'Another way to make Cowslip Wine 'Having boil'd your Water and Sugar together, pour it boiling hot upon your Cowslips beaten, stir them well together, and let them stand in a Vessel close cover'd till it be almost cold.
The best form to take it for a complaint in the intestines is as follows: To an ounce of the fresh root bruised add an ounce and a half of the fresh roots of white beets and a quart of water, boiling hot and let it stand till next day, then drain it off.
We were barely a quarter of the way up the cliff face when the flood smashed against the base of the rocks, splashing boiling hot foam against me and sending Dal spinning on the end of the rope.
It's boiling hot out there, and it's getting nearly as bad in the car.
Daniel opened his mouth to protest, and then hurriedly shut it again as boiling hot steam hit him from all sides at once.
You want water thrown over you, sometimes boiling hot, sometimes freezing cold?