Last spring frost
May 10
Frost Dates for Pablo, MT
First fall frost
Oct 5
Growing season
147 days
Hardiness zone
6a
In an average year around Pablo, MT, the last spring frost (32°F) is about May 10 and the first fall frost is about Oct 5, giving roughly a 147-day growing season. To be safe most years, wait until Apr 27 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Jun 16 | May 28 | May 11 |
| Freeze (32°F) | May 26 | May 10 | Apr 27 |
| Hard (28°F) | May 13 | Apr 28 | Apr 7 |
| Severe (24°F) | Apr 30 | Apr 6 | Mar 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 16 | Jun 10 | Jun 4 | May 31 | May 28 | May 24 | May 21 | May 16 | May 11 |
| 32°F | May 26 | May 21 | May 17 | May 13 | May 10 | May 7 | May 5 | May 1 | Apr 27 |
| 28°F | May 13 | May 7 | May 3 | May 1 | Apr 28 | Apr 24 | Apr 19 | Apr 14 | Apr 7 |
| 24°F | Apr 30 | Apr 23 | Apr 16 | Apr 11 | Apr 6 | Apr 1 | Mar 29 | Mar 22 | Mar 12 |
| 20°F | Apr 11 | Apr 1 | Mar 27 | Mar 21 | Mar 16 | Mar 10 | Mar 6 | Mar 2 | Feb 25 |
| 16°F | Mar 24 | Mar 17 | Mar 11 | Mar 7 | Mar 3 | Feb 28 | Feb 24 | Feb 18 | Feb 10 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 9 | Sep 26 | Oct 7 |
| Freeze (32°F) | Sep 22 | Oct 5 | Oct 19 |
| Hard (28°F) | Oct 1 | Oct 16 | Nov 1 |
| Severe (24°F) | Oct 11 | Oct 27 | Nov 14 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 9 | Sep 15 | Sep 20 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 7 |
| 32°F | Sep 22 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 19 |
| 28°F | Oct 1 | Oct 5 | Oct 9 | Oct 13 | Oct 16 | Oct 18 | Oct 22 | Oct 25 | Nov 1 |
| 24°F | Oct 11 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 2 | Nov 7 | Nov 14 |
| 20°F | Oct 20 | Oct 26 | Oct 31 | Nov 3 | Nov 7 | Nov 10 | Nov 14 | Nov 19 | Nov 26 |
| 16°F | Oct 29 | Nov 4 | Nov 9 | Nov 13 | Nov 18 | Nov 22 | Nov 26 | Dec 2 | Dec 11 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Polson, Mt, about 6.2 miles away@if(!empty($station['elevation_ft'])), at 3,010 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Pablo, MT?
On average, the last spring frost (32°F) around Pablo, MT is about May 10. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 27.
When is the first frost in the fall?
The first fall frost around Pablo, MT typically arrives about Oct 5. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around May 10 on average, or Apr 27 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 147 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 59855 Planting calendar → Montana frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026