Flathead County, Montana · Frost dates
Flathead County frost dates.
First-frost, last-frost, and growing-season length for Flathead County, Montana. Sourced from NOAA 1991-2020 Climate Normals.
Data confidence: high · USDA zone: 4b
32°F — light freeze
Last spring frost
- 10%
- 05-30
- 20%
- 05-23
- 50%
- 05-09
- 80%
- 04-30
- 90%
- 04-25
First fall frost
- 10%
- 09-13
- 20%
- 09-21
- 50%
- 10-01
- 80%
- 10-10
- 90%
- 10-17
28°F — killing freeze
Last spring freeze
- 10%
- 05-14
- 20%
- 05-07
- 50%
- 04-27
- 80%
- 04-15
- 90%
- 04-08
First fall freeze
- 10%
- 09-30
- 20%
- 10-04
- 50%
- 10-14
- 80%
- 10-26
- 90%
- 10-31
Growing season length (days, 28°F threshold)
- Short year
- 139
- Median
- 170
- Long year
- 206
Source NOAA station
HUNGRY HORSE DAM, MT US
3.5 mi · 30 yrs of record (1991–2020) · 3160 ft elev.
Data from HUNGRY HORSE DAM, MT US, 3.5 miles away with 30-year NOAA record (1991-2020).
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