Important: The Climate Analysis Branch (PSD1) web site will be down in anticipiation of our major web restructuring starting Tuesday Jan 20th at 1pm MST.
You can find more info about the upcoming URL changes here.
You can find more info about the upcoming URL changes here.
First Day of Frost in Boulder
Data from 1957-1995
Frost is defined here as the minimum temperature being less than or equal to 32 F. Frost may occur even when the official temperature is above 32F as the ground can be colder than where the thermometer is located (typically 3 meters above the surface).
earliest day of frost: Sep 12 (1974) latest day: Oct 31 (1963) average: Oct 6 first quartile Sep 25 median Oct 5 third quartile Oct 18 standard deviation 13.6 days