10/12/2017 - The average date of the first freezing temperature of the fall in north central Iowa is October 4th. In one-half of all the years in recorded history the first freeze occurs within one week of October 4th. However, there is considerable variability.
Iowa State Climatologist Harry Hillaker tells Radio on the Go News that in Hampton the first freeze has come as early as September 11th in 1955 and as late as November 2nd in 1936.
Elsewhere in north central Iowa the first freeze has come as early as August 20th in Britt in 1950 and as late as November 8th at Algona in 1900 and Clear Lake in 1904.