The coldest temperature ever recorded on earth is -89.2 degrees Celsius (-128.5 degrees Fahrenheit) at Vostok, Antarctica on July 21, 1983. That all-time low broke the previous world-record minimum of -88.3 °C (-126.9 °F), set on August 24, 1960, also at Vostok.
Vostok is a Russian research station located high in the middle of the East Antarctic ice sheet, about 1,300 kilometres from the geographic South Pole.
This is a place where the sun doesn't rise during winter. Besides being extremely far south, the station's high elevation, at 3,420 metres (11,220 feet), helps it get really cold.
The conditions that caused the temperature to drop exceptionally low at Vostok in July 1983 were clear skies accompanied by calm air. Vertical mixing of the air was minimal and no wind had stirred for some time.
Vostok is not an outlier in the Antarctic temperature regime. On July 20th, 1968, the temperature at another high elevation research base, called Plateau Station, sank to -86.2 °C (-123.1 °F).