Green’s Dictionary of Slang

(US) extremely.

1985		(con. 1969–70) D. Bodey F.N.G. (1988) 2: Ungoddamly hot here. I’d rather be home. [Ibid.] 5: On two hits I get ungodly high.
2012		L. Berney Whiplash River [ebook] Ungodly fast, you wouldn’t believe it.