The phrase "big freeze" refers to an extreme period of very cold weather that lasts for a long time, causing freezing temperatures and icy conditions. Full definition
So you can put really big, I mean we're talking like big frozen food — family sized. (twiniversity.com)
Snow in a way it hadn't for almost twenty years, since the last big freeze in 1985. (bookbrowse.com)
Fast - forward to last year when much the opposite prediction was being trumpeted by the London Daily Mail Online, which headlined «Britain faces coldest winter for 100 years as Big Freeze follows floods with wind so strong it blows water upwards.» (wnd.com)