Plant By Frost

Montana

Frost dates for Libby 1 Ne Rs, MT

At this NOAA station the last spring frost (32°F) usually comes by May 23 and the first fall frost around September 21, giving a growing season of about 120 days.

May 23average last spring frost
September 21average first fall frost
JanAprJulOctDec

Frost odds

1 year in 10 the last spring frost is later thanJune 7
Half of years the last spring frost is later thanMay 23
9 years in 10 the last spring frost is later thanMay 9
1 year in 10 the first fall frost is earlier thanSeptember 3
Half of years the first fall frost is earlier thanSeptember 21
9 years in 10 the first fall frost is earlier thanOctober 8

A hard freeze (28°F) usually ends by May 7 and returns around October 5.

Station USC00245015, elevation 639 m. Based on 24 years of 1991 to 2020 records. A garden higher up, in a hollow or far from this station can freeze later in spring.

Check another ZIP

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