"There is frost just now."
Translation:Tha reòthadh ann an-dràsta.
No -- a-muigh means out, or outside.
"Ann" roughly means "there", as in "there is frost." See the tips and notes here: https://www.duolingo.com/skill/gd/Rain/tips-and-notes Or have a look at Wiktionary, here: https://en.wiktionary.org/wiki/ann#Scottish_Gaelic