Green’s Dictionary of Slang

(Irish) mentally unbalanced, fey.

1932		S. O’Faoláin Midsummer Night Madness and Other Stories n.p.: After he died she went a bit airy so they had to bring her to us.
1939		J. Steinbeck Grapes of Wrath (1951) 160: ‘What’s eatin’ Granma?’ ‘I don’t know. ’Member the las’ couple days she’s been airy-nary, sayin’ nothin’ to nobody?’.