Cold is a fact of life in Canada in the winter - but there are a few pockets of the country, like coastal BC, the Okanagan Valley and Niagara, where the temperature rarely goes below -20C. That's the point at which wine grape vines start to die.

Some Okanagan wineries were busy picking their icewine grapes in mid-December as temperatures fell below the -8C threshold. Mission Hill winery issued a press release on December 17 quoting winemaker John Simes on how the unusually early deep-freeze "has resulted in fruit that is in excellent condition." The press release also noted that the temperatures were "between -12C and -21C, depending on the wind chill."

A few days later, things got a lot colder.

Native grapes from eastern North America - from the vitis labrusca family - can handle the deadly winters of northern New York and Southern Ontario, where -20C temperatures happen every few years. However, the "noble" grape varietals that the good wines come from are the more sensitive vitis vinifera - a European family of grapes originating in the mild Mediterranean region. They're the big ones: cabernet sauvignon, chardonnay, merlot, syrah, etc. Over the centuries, more cold hardy "clones" of various vinifera grapes have permitted successful cultivation as far north as the middle of Germany, southern England and, of course, Ontario and BC. The most cold hardy are riesling, chardonnay and cabernet franc - whaddya know... Ontario's best!

Niagara suffered deadly cold in the winter of 2003 - over one third of the region's vines were damaged or killed, resulting in several years of "short" crops as new plantings matured to the point they could produce viable fruit. That year, Niagara experienced several nights of temperatures between -23 and -26. At the time, I interviewed Daniel Speck of Henry of Pelham for his take on the situation. The good news for Okanagan is that this cold snap is happening now rather than in February. Speck said that "we hit -23 in December and there were several very cold nights in January, but the damage was minimal. But there was one night in late February when the temperature dropped very quickly to the -20 range and that seemed to be the one that did the damage. The days are getting longer by then and the vines start to come out of dormancy."

The December 17-26 cold snap in the Okanagan was actually worse than Niagara circa 2003. Check this December 19th forecast for Kelowna, home to a number of big wineries, including Mission Hill and Quail's Gate. At left is a screen shot courtesy of Environment Canada summarizing the situation for the weekend - it was even colder than forecast on the Friday and the Saturday low turned out to be a deadly -30.

The southern Okanagan, however, seems to have dodged the bullet.

Before visiting the Okanagan last summer, I spoke to David Phillips, a meteorologist at Environment Canada here in Toronto. He supplied a lot of figures about the climate and noted that there seemed to be a point just south of Penticton where it was definitely warmer and drier. He couldn't explain it, having visited the area a long time ago, but suggested it had to do with elevation: the southern Okanagan is closer to sea level than the northern part. But you can go on to Google Earth and see that there are some impressively massive mountains south of Okanagan Falls that really delineate the north and south Okanagan. Highway 97 is no longer hugging a lake at this point: there is no lake. It squeezes through the mountains that protect the southern Okanagan from the northern nastiness and then runs into the flatlands of Oliver and Osoyoos - the hottest places in Canada. Some of BC's best wineries - including Osoyoos Larose and Sumac Ridge are south of that point and, yes, they are closer to sea level. Mission Hill also has vineyards right on the US border.

On the same night Kelowna was -27, Osoyoos was a positively balmy -14. It hit -19 on the 20th, but that was the trough.

Ontario's current - and annoying - "snowmageddon" won't cause any problems for the Niagara  vines. Snowdrifts notwithstanding, Niagara-on-the-Lake bottomed out at -10 on Friday the 19th and has been warmer ever since.