A: No one keeps records of wind chill "temperatures." To begin with, the wind chill value is not a temperature even though it's expressed that way.
That said, the coldest wind chills would have to be in Antarctica during the June through August winter. For instance, at the US South Pole Station, the average low temperature for the months of July, August and September is -81 degrees. Winds are generally light on the Antarctic Plateau, where the Pole is located. But, if the wind were only 10 mph on an average August day with a low of -81, the wind chill would be -116. If the wind were 25 mph, which happens at the South Pole in the winter, the wind chill would be -132 degrees.
While winds are generally calm in the middle of Antarctica, they normally howl during the winter around the edges of the continent. For example, at the US McMurdo Station the average low in August is -25 degrees — much warmer than the Pole — but August winds have been recorded at 100 mph, or even faster. A -25 temperature and a wind of
100 mph gives a wind chill of-77.
These figures are all lower than the National Weather Service's wind chill table, which goes down only to -25 degrees and a wind of 60 mph for a chill of -69. The wind chill part of the weather calculator on the Web site of the National Weather Service's St. Louis office was used to calculate the values in this answer.
Jack Williams, weather editor