White Christmases are becoming less common in Halifax, but why?

Whether you love it or hate it, snow can be an added touch when waking up on Christmas morning.

While it may be too early to determine whether or not Halifax will have a white Christmas this year, data suggests the odds of having one are decreasing and that climate change may be to blame.

“It's getting less and less, there's something about your climate that is maybe warming or wetting up, you're more likely to get rain than snow,” Environment Canada Senior Climatologist David Phillips said. “It's not a done deal.”

While there is no universal definition of a white Christmas, Environment Canada defines one as having at least 2 cm of snow on the ground at 7 a.m. Christmas morning. A “perfect Christmas” is a white Christmas morning and snow in the air at some point on Christmas day. 

Decreasing odds of a white Christmas

Environment Canada has compiled historical snowfall data for 45 major centres, including Halifax, analyzing 63 years of weather records between 1955 and 2017 to calculate the probability of having a white Christmas.

Between 1955 and 2017 there was a 54 per cent chance of a white Christmas in Halifax. When you narrow the numbers, the odds of one drop to just 40 per cent from the period between 1994 and 2017. Compare that to the period from 1965 to 1984 when the odds of a white Christmas were about 65 per cent. Environment Canada says the change in frequency over 30 years has dropped by 25 per cent.

There were 10 green Christmases during a 30-year period between 1955 and 1985. That number has doubled in the past 32 years to 20 from the period between 1986 and 2018.

“It's not something that is really a slam dunk as it used to be, it's more I would bet a loonie or two in the fact that you wouldn't have a white Christmas in any particular year,” Phillips said. 

The average snow depth on Christmas Day has also dropped – from an average of 9 cm on the ground between 1965 and 1984 to the white Christmas threshold of 2 cm from 1994 to 2017.

The climate change factor

Phillips points to Halifax's marine climate along with climate change as possible factors for the decreasing odds of a white Christmas.

“What we do know is that we're seeing less snow in the southern part of the country, we're seeing warmer temperatures, particularly in the wintertime,” Phillips said. “All you need is a difference of one or two degrees, which can make a difference between whether you're going to get the white stuff or the liquid stuff.”

Phillips says Halifax's weather has become variable in the winter-time with swings between frigid arctic air and balmy southerly air all part of our weather now.

“So kids are going to have to either dream a little harder or even pray or beg for a white Christmas, it's just not in the cards,” Phillips said. “It's just not something you can expect even once every two years.”

Halifax “long overdue” for a white Christmas

The last white Christmas in Halifax was in 2013 when 4 cm of snow was recorded on the ground at Halifax Stanfield International Airport. The following Christmas in 2014 featured 41.8 mm of rain and a record-breaking high temperature of 16.6°. While snow was reported at times on Christmas day in 2018, only trace amounts of snow were recorded, falling short of meeting Environment Canada's criteria. 

“We really have seen a fundamental change to conditions in the Halifax area and it's been something that we've seen right across the country too,” Phillips said.

Phillips says while the forecast can still change and a system could sneak in some snowfall, he expects the trend streak of green Christmases could continue again this year.

“You're going to have to hope and pray that you're going to get some snow during that, say, the week prior to Christmas and you know it doesn't look good,” Phillips said. “Things can change.”

“A white Christmas is just part of our past but doesn't seem to be part of our future.”