“Wind chill” is a measure of how much colder you would “feel” if cold air is blowing on you with a particular wind speed. The higher the wind speed and the lower the temperature, the colder the wind chill temperature. The colder the wind chill, the faster you could experience hypothermia and suffer severe health consequences. Here is a link to NOAA’s wind chill chart: http://www.nws.noaa.gov/om/cold/wind_chill.shtml. The coldest wind chill I have ever been out in was about -60 F when I was living in Wisconsin (also around MLK Jr. Day). Note that it is not a real measurable temperature, just something that is calculated to provide a rough estimate of the additional cooling power caused by the icy wind stripping heat away from your body.
The prediction for tomorrow’s wind chill in Atlanta, for example, is approximately 0 F. But in the past it has been hard to find wind chill climatologies (think of trying to answer a question like how often do we get wind chills below 10 F?) because wind chill is not a climate variable that is archived. That means it has to be recalculated each time you want to study it. But now, the Midwestern Regional Climate Center has included wind chill and apparent temperature (for those hot and humid summer days) in their list of threshold values that can be analyzed.
Just for fun, I calculated the total number of hours in Atlanta that were at or below a wind chill of 0 F in 2009 to 2018 and found that the total number of hours was 35, all but one in January. Note that because of the large number of hours and the calculation that needs to be done, it takes a while to get an answer, and it choked when I tried to do the period of record for the Atlanta airport. But it is an interesting new tool that you might find useful to answer those odd questions that reporters, school children and bar patrons love to ask.
To use the tool, you first need to set up a free account at http://mrcc.isws.illinois.edu/CLIMATE. Then pick an hourly station and pick Frequency Distribution from the Hourly-Observed Data tab. Note that they are not kidding when they say it can take several minutes to create the table, so you might want to start with just a few years before you tackle large chunks of data.
Stay warm and keep a winter survival kit in your car if you have to go out in dangerously cold conditions!