Freeze and Frost Summary

growing season  |  number of days from the last recorded 32 degrees in spring to the first recorded 32 degrees in autumn.

Climate_Frostfrost  |  32°F or lower          freeze  |  28°F or lower.

The following statistics were compiled from temperature observations recorded at the Flagstaff-Pulliam Airport, between the years of 1950 – 2013 (or 2014 where available). Observations prior to 1950 were not included, as they were not made at Flagstaff Pulliam Airport. However, based solely on lowest monthly average temperatures from 1971 – 2000, Flagstaff records indicate that an average year now has 206 days with temperatures of 32°F or lower, and 6 days with temperatures 0°F or lower. The warmest days of the year can be generally expected from the first week of July to around July 20.

Average Dates for the freezes and frosts for the spring and fall seasons are as follows:
  • Last Freeze of Spring Season: May 28
  • Last Frost of Spring Season: June 9
  • First Frost of Fall Season: September 24
  • First Freeze of Fall Season: October 5
  • Average Growing Season: 103 days
  • Shortest Growing Season: 72 days – 1968 
  • Longest Growing Season: 145 days – 1981
Still, freezing temperatures have been recorded in every month of the year for the Flagstaff area. The most extreme events are as follows:
  • Earliest final Spring freeze: April 23, 1992
  • Latest final Spring freeze: June 27, 1965
  • Earliest final Spring frost: April 30, 2009
  • Latest final Spring frost: July 8, 1955
  • Earliest first Fall frost: August 22, 1968
  • Latest first Fall frost: October 14, 1981
  • Earliest first Fall freeze: August 23, 1968
  • Latest first Fall freeze: October 27, 2010

— statistics compiled by Dan Stewart