It'll be a long day in January

It'll be a long day in January (when something happens).

Rur. Something will never happen. (There are fewer hours of daylight in January.) Tom: Maybe this will be the year that Mama treats herself to a nice vacation. Jane: Are you kidding? It'll be a long day in January when she does that! It'll be a long day in January when that car dealer gives an honest price.
See also: January, long
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • If that don't beat a pig a-pecking!
  • if you've a mind to do
  • whistlin' Dixie, you ain't just
  • I swan!
  • go at like a boy killing snakes
  • have hung up and salted
  • in an age of years
  • howdy and a half
  • I've done my do
  • If it ain't chickens, it's feathers