Boulder, Colorado Weather and Climate

First Day of "Frost" in Boulder

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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).


Data from 1948-2014

earliest day of frost: Aug 30 (1981)
latest day: Oct 31 (1963)
average: Oct 4
first quartile: Sep 25
median: Oct 4
third quartile: Oct 14
standard deviation: 13.7 days

Data from 1897-2014

earliest day of frost: Aug 30 (1981)
latest day: Oct 31 (1963)
average: Oct 4
first quartile: Sep 25
median: Oct 4
third quartile: Oct 14
standard deviation: 13.7 days