Green’s Dictionary of Slang

God-awful adj.

(orig. US) especially appalling; also God-awfullest.

[US]J.H. Beadle Western Wilds 611: Raised a little corn and oats in 1873, and put thirty acres [...] into wheat and went to work with a hurrah in 1874 to make a God-awful crop.
[UK]Hall & Niles One Man’s War (1929) 290: Some God-awful place in southern Italy.
[US]W.R. Burnett Iron Man 119: She’s down in some God-awful rooming house.
[US] in V. Randolph Pissing in the Snow (1988) 91: Jack pulled out the God-awfullest tool you ever seen.
[UK]J. Maclaren-Ross Of Love and Hunger 23: Playfair’s been raising ruddy hell. Gave me a god-awful rolluxing Monday.
[UK]J. Osborne Epitaph for George Dillon Act II: This hideous, God-awful room!
[UK]J. Barlow Burden of Proof 17: It was some God-awful hour of the morning like eleven o’clock.
[US]A. Maupin Tales of the City (1984) 124: We get up at some godawful hour of the morning.
[UK]T. Paulin ‘From ‘Landsflykt’ Fivemiletown 44: Away to hell, England [...] your cheapo novels your daily Godawful papers.
[Ire]M. Verdon Shawlies, Echo Boys, the Marsh and the Lanes 91: Somehow, God willing, we got through the ’20s and ’30s [...] They say now they were the best of times but don’t let them cod you. They were God-awful years.
[US]C. Cook Robbers (2001) 58: Her hair was a godawful mess, kinked up in back, bangs all aflutter.
[Aus]L. Redhead Rubdown [ebook] They started playing god-awful Australian rap.
[US]C. Hiaasen Nature Girl 133: I had a god-awful nightmare.
[Aus]J.J. DeCeglie Drawing Dead [ebook] Worbich was a god-awful parasite, but [...] his girl Hannah was a peach.
[US]S.A. Crosby Blacktop Wasteland 87: The god-awful clusterfuck that was Interstate 64.