The largest recorded snowflake was in Keogh, Montana in 1887. It was 15 inches wide.
The phenomenon was witnessed by the personnel at Fort Keogh, and the reports are reliable enough that Guinness World Records has certified that monster snowflake to be the largest ever recorded.
Learn about the most snow to fall in one day.
Learn about the day it rained frogs in Kansas City, Missouri.
Read about other Guinness world records.