Last spring frost
Jun 18
Frost Dates for Clancy, MT
First fall frost
Sep 5
Growing season
81 days
Hardiness zone
4b
In an average year around Clancy, MT, the last spring frost (32°F) is about Jun 18 and the first fall frost is about Sep 5, giving roughly a 81-day growing season. To be safe most years, wait until May 30 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%) |
|---|---|---|---|
| Freeze (32°F) | Jul 3 | Jun 18 | May 30 |
| Hard (28°F) | Jun 19 | May 29 | May 12 |
| Severe (24°F) | May 28 | May 12 | Apr 27 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 3 | Jun 28 | Jun 24 | Jun 21 | Jun 18 | Jun 14 | Jun 10 | Jun 4 | May 30 |
| 28°F | Jun 19 | Jun 11 | Jun 6 | Jun 1 | May 29 | May 25 | May 21 | May 18 | May 12 |
| 24°F | May 28 | May 21 | May 17 | May 14 | May 12 | May 8 | May 5 | May 2 | Apr 27 |
| 20°F | May 12 | May 7 | May 3 | Apr 30 | Apr 28 | Apr 24 | Apr 20 | Apr 15 | Apr 8 |
| 16°F | May 3 | Apr 28 | Apr 23 | Apr 17 | Apr 13 | Apr 8 | Apr 5 | Apr 2 | Mar 27 |
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%) |
|---|---|---|---|
| Freeze (32°F) | Aug 21 | Sep 5 | Sep 18 |
| Hard (28°F) | Sep 4 | Sep 18 | Oct 1 |
| Severe (24°F) | Sep 17 | Oct 1 | Oct 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 21 | Aug 27 | Aug 30 | Sep 2 | Sep 5 | Sep 8 | Sep 11 | Sep 14 | Sep 18 |
| 28°F | Sep 4 | Sep 10 | Sep 13 | Sep 16 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Oct 1 |
| 24°F | Sep 17 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 16 |
| 20°F | Sep 26 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 18 | Oct 21 | Oct 30 |
| 16°F | Oct 2 | Oct 8 | Oct 14 | Oct 17 | Oct 21 | Oct 25 | Oct 30 | Nov 3 | Nov 9 |
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: Tizer Gardens, Mt, about 5 miles away@if(!empty($station['elevation_ft'])), at 4,672 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 Clancy, MT?
On average, the last spring frost (32°F) around Clancy, MT is about Jun 18. In cooler years it can run later, so for a safer bet many gardeners wait until May 30.
When is the first frost in the fall?
The first fall frost around Clancy, MT typically arrives about Sep 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 Jun 18 on average, or May 30 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 81 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 59634 Planting calendar → Montana frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026