How big and hot can black holes get?

Actually, the biggest black holes are the coldest because their so-called Hawking temperature is measured in billionths of a degree above absolute zero. The hottest black holes are microscopic and have less than 1 trillion grams of mass, and temperatures that increase from a million degrees to trillions of degrees as they evaporate.

Quantum black holes which have masses of 0.00001 grams have sizes equal to 10^-33 centimeters and their evaporation temperatures are 10^32 degrees, making them the hottest possible objects in the universe...if they exist.