Winter's Oscillating Temperatures

So far, we have seen some highs and lows for our winter of 2013-2014. We recently met with a group of winemakers and vineyard managers and their assistants at Dave's home and we spoke to them about low temperatures during the dormant season. Mike McAndrew, vineyard manager at Stonington Vineyards recalled the winter of 2008 when there were several days of subzero temperatures. That year, the merlot that Dave was managing took a hit. Being newly minted farmers, we are keen weather-watchers and cross our fingers that our vines have been handling the occasional subzero temperatures that we have been having.
On the AccuWeather.com Site, the summary of the temperature for the month of December 2013 looks like this:

During the few days before Christmas, we had some very warm temperatures and then on Christmas Day, it was cold, but brutal cold temperatures were yet to arrive. So far, for 2014, we have had single digit and subzero temperatures on January 3, 4 and 5. This brutally cold weather was brought to us by something called the polar vortex. I keep a weather diary for our vineyard, but we are talking about putting a weather station on our property to accurately measure the daily temperature fluctuations.