Frost dates · Montana
Montana frost dates,
county by county.
Last spring frost and first fall frost probability data for all 56 counties in Montana, computed from the NOAA 1991–2020 Climate Normals. Every county page surfaces the full probability table at three temperature thresholds plus crop-specific planting guidance.
Variation across Montana
885 days separate the earliest and latest counties.
The median last spring frost in Dawson County is April 24 — 885 days earlier than Sanders County at —. Statewide averages aren't useful planting tools; pick your county below for the data that actually applies to your fields.
By frost timing
Counties sorted by last spring frost.
Latest at top, earliest at bottom. In most states this matches the north-to-south gradient.
- Sanders CountySpring —·Fall —0-day season
- Beaverhead CountySpring May 30·Fall Sep 14107-day season
- Granite CountySpring May 29·Fall Sep 12106-day season
- Powell CountySpring May 26·Fall Sep 11108-day season
- Jefferson CountySpring May 21·Fall Sep 21123-day season
- Silver Bow CountySpring May 21·Fall Sep 17119-day season
- Daniels CountySpring May 19·Fall Sep 16120-day season
- Glacier CountySpring May 19·Fall Sep 20124-day season
- Meagher CountySpring May 18·Fall Sep 25130-day season
- Wibaux CountySpring May 17·Fall Sep 26132-day season
- Sheridan CountySpring May 15·Fall Sep 22130-day season
- Madison CountySpring May 14·Fall Oct 1140-day season
- Roosevelt CountySpring May 14·Fall Sep 22131-day season
- Teton CountySpring May 14·Fall Sep 25134-day season
- Deer Lodge CountySpring May 13·Fall Sep 28138-day season
- Stillwater CountySpring May 13·Fall Sep 26136-day season
- Hill CountySpring May 12·Fall Sep 26137-day season
- Wheatland CountySpring May 12·Fall Sep 27138-day season
- Custer CountySpring May 11·Fall Sep 25137-day season
- Liberty CountySpring May 11·Fall Sep 26138-day season
- Big Horn CountySpring May 10·Fall Sep 28141-day season
- Judith Basin CountySpring May 10·Fall Oct 1144-day season
- Toole CountySpring May 10·Fall Sep 26139-day season
- Chouteau CountySpring May 9·Fall Sep 29143-day season
- Garfield CountySpring May 8·Fall Sep 29144-day season
- Broadwater CountySpring May 7·Fall Oct 1147-day season
- Lewis and Clark CountySpring May 7·Fall Sep 28144-day season
- Lincoln CountySpring May 7·Fall Oct 5151-day season
- Musselshell CountySpring May 7·Fall Oct 1147-day season
- Petroleum CountySpring May 7·Fall Sep 29145-day season
- Blaine CountySpring May 6·Fall Sep 30147-day season
- Carter CountySpring May 6·Fall Oct 1148-day season
- McCone CountySpring May 6·Fall Oct 1148-day season
- Golden Valley CountySpring May 5·Fall Oct 3151-day season
- Ravalli CountySpring May 5·Fall Oct 4152-day season
- Park CountySpring May 4·Fall Oct 5154-day season
- Pondera CountySpring May 4·Fall Oct 4153-day season
- Powder River CountySpring May 3·Fall Oct 7157-day season
- Valley CountySpring May 3·Fall Oct 5155-day season
- Fallon CountySpring May 2·Fall Oct 4155-day season
- Fergus CountySpring May 2·Fall Oct 6157-day season
- Gallatin CountySpring May 2·Fall Oct 3154-day season
- Richland CountySpring May 2·Fall Oct 6157-day season
- Sweet Grass CountySpring May 2·Fall Oct 5156-day season
- Carbon CountySpring May 1·Fall Oct 4156-day season
- Mineral CountySpring May 1·Fall Oct 6158-day season
- Prairie CountySpring May 1·Fall Oct 5157-day season
- Cascade CountySpring Apr 30·Fall Oct 8161-day season
- Phillips CountySpring Apr 30·Fall Oct 6159-day season
- Treasure CountySpring Apr 30·Fall Oct 7160-day season
- Yellowstone CountySpring Apr 30·Fall Oct 4157-day season
- Rosebud CountySpring Apr 29·Fall Oct 8162-day season
- Lake CountySpring Apr 28·Fall Oct 16171-day season
- Missoula CountySpring Apr 28·Fall Oct 12167-day season
- Flathead CountySpring Apr 27·Fall Oct 14170-day season
- Dawson CountySpring Apr 24·Fall Oct 13172-day season
Alphabetical
All Montana counties — A to Z.
- Beaverhead County
- Big Horn County
- Blaine County
- Broadwater County
- Carbon County
- Carter County
- Cascade County
- Chouteau County
- Custer County
- Daniels County
- Dawson County
- Deer Lodge County
- Fallon County
- Fergus County
- Flathead County
- Gallatin County
- Garfield County
- Glacier County
- Golden Valley County
- Granite County
- Hill County
- Jefferson County
- Judith Basin County
- Lake County
- Lewis and Clark County
- Liberty County
- Lincoln County
- Madison County
- McCone County
- Meagher County
- Mineral County
- Missoula County
- Musselshell County
- Park County
- Petroleum County
- Phillips County
- Pondera County
- Powder River County
- Powell County
- Prairie County
- Ravalli County
- Richland County
- Roosevelt County
- Rosebud County
- Sanders County
- Sheridan County
- Silver Bow County
- Stillwater County
- Sweet Grass County
- Teton County
- Toole County
- Treasure County
- Valley County
- Wheatland County
- Wibaux County
- Yellowstone County