
Considering that it was able to melt through rock with enough power to reach the center of the Earth, I would say that it's extremely hot, though I don't know the exact temperature. One guidebook stated that Godzilla's (specifically the Heisei version's) atomic breath was about 500,000 degrees Celsius or 900,032 degrees Fahrenheit, not sure exactly how accurate that is (since that's apparently over 85 times hotter than the surface of the Sun, if the articles I read are correct), but if it is, then I assume that the MonsterVerse version would be similar.

Keep in mind that I'm going off of calculations from other articles and an official Godzilla guidebook (which might have some mistranslations and errors), so I might be completely wrong, because, in all honesty, I really suck at math.