12/20/2013 11:51 EST | Updated 02/19/2014 05:59 EST

What's the definition of a 'white Christmas'?

Are you wondering if you'll have a white Christmas this year?

With the big day just around the corner, many of you probably know already whether it's looking like a green or a white one. To count officially as a white Christmas, your location must have at least 2 cm of snow on the ground at 7 a.m. on Dec. 25.

But do you know what your chances are every year, and how that has changed across Canada since the 60s and 70s?

In this week's Science Smart video column, Johanna Wagstaffe will take a look at the odds across the country now and 40 years ago. (Click on the video above.) 

If you have a science question you'd like answered, send Johanna a tweet (@JWagstaffe) or an email: