The lowest reliably-measured, naturally-occurring temperature on the Earth's surface happened about 800 miles East of the South Pole and at an altitude of 11,444 feet, on July 21, 1983. There, temperatures dropped to minus 126.6 degrees Fahrenheit.
The site is Vostok Station, Antarctica, a Russian research outpost whose fields of inquiry include hot cocoa, fuzzy socks, and getting dressed very quickly in the morning. It is one of the most inaccessible and inhospitable places on Earth. Some 25 scientists live there in the summer, where temperatures get up to a relatively pleasant minus 25 degrees F. Only 13 or so remain there through the long winter, when the mercury plunges to minus 85 degrees F. (We mean that metaphorically, because mercury actually freezes solid at around 40 below zero.)