By the numbers Chilling winter numbers


15 inches wide: The largest snowflake ever measured, according to the Guinness World Records. And it was 8 inches thick. Observed in 1887 at Fort Keogh, Montana.

10 to 1: The commonly used ratio of snow to rain. (10 inches of snow = 1 inch of rain) However, the ratio actually can vary from 100 to 1 for extremely dry snow to 3 to 1 for extremely wet snow.

75.8 inches: The official world record for a 24-hour snowfall, set on April 14-15, 1921, in Silver Lake, Colo. Another record, although not official, is the 70.9 inches of snow that fell in 15 hours in Dartmoor, England, on Feb. 16, 1929.

-81 degrees: The average low temperature for the months of July, August and September at the U.S. South Pole Station. (If the wind were 25 mph, which happens at the South Pole in the winter, the wind chill would be -132 degrees.