Plant By Frost

Colorado

Frost dates for Bonny Dam 2Ne, CO

At this NOAA station the last spring frost (32°F) usually comes by May 5 and the first fall frost around October 10, giving a growing season of about 155 days.

May 5average last spring frost
October 10average first fall frost
JanAprJulOctDec

Frost odds

1 year in 10 the last spring frost is later thanMay 19
Half of years the last spring frost is later thanMay 5
9 years in 10 the last spring frost is later thanApril 21
1 year in 10 the first fall frost is earlier thanSeptember 28
Half of years the first fall frost is earlier thanOctober 10
9 years in 10 the first fall frost is earlier thanOctober 21

A hard freeze (28°F) usually ends by April 25 and returns around October 18.

A light frost (36°F, which can still nip tender plants) usually ends by May 15 and returns around October 1.

Station USC00050834, elevation 1133 m. Based on 25 years of 1991 to 2020 records. A garden higher up, in a hollow or far from this station can freeze later in spring.

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Sources

  1. U.S. Annual/Seasonal Climate Normals, 1991 to 2020 (freeze probability dates by station), NOAA National Centers for Environmental Information, checked 1 November 2026
  2. Annual/Seasonal Normals 1991 to 2020 documentation, NOAA National Centers for Environmental Information, checked 1 November 2026
  3. 2024 Gazetteer Files, ZIP Code Tabulation Areas, US Census Bureau, checked 1 November 2026