apparently, 37 C as posted previous. sorry i couldnt give you a number, but so many things contribute to boiling points, its kind of trial and error. do you own a double boiler? because that would be best, one pot with boiling water on the stove, another pot that fits into the top of it that you put your butter in. the hot water melts the butter without boiling anything! perfect. and don't worry about the straining if youre using hash, it doesnt need to be strained. only if you have chunks of weed in it. i think you could consider steaming without boiling a good temp.