This, from State College-based AccuWeather, the world's largest private weather forecaster:

In the Northern Hemisphere, the darkest quarter of the year runs from the first week in November through the first week of February.

This period is referred to as Solar Winter. Long-term averages show the coldest quarter of the year as being from early December through early March.

This is what we call Meteorological Winter. Astronomical winter (approx. June 21 until March 21) is determined by the Earth's position with respect to the sun and only loosely correlates with temperature normals (averages).

Of course this doesn't mean much today and will mean less tonight and tomorrow. Wind chill values are expected to fall to minus-10 degrees and lower tonight and Friday.

Worse, even colder air is being forecasted for the middle of next week.

- Jeffrey L. Frischkorn
JFrischkorn@News-Herald.com