Last spring frost
May 23
Frost Dates for Mass City, MI
First fall frost
Oct 1
Growing season
128 days
Hardiness zone
4b
In an average year around Mass City, MI, the last spring frost (32°F) is about May 23 and the first fall frost is about Oct 1, giving roughly a 128-day growing season. To be safe most years, wait until May 6 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 29 | Jun 7 | May 24 |
| Freeze (32°F) | Jun 8 | May 23 | May 6 |
| Hard (28°F) | May 24 | May 6 | Apr 24 |
| Severe (24°F) | May 8 | Apr 25 | Apr 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 29 | Jun 20 | Jun 15 | Jun 11 | Jun 7 | Jun 4 | Jun 1 | May 28 | May 24 |
| 32°F | Jun 8 | Jun 2 | May 31 | May 27 | May 23 | May 20 | May 16 | May 12 | May 6 |
| 28°F | May 24 | May 18 | May 13 | May 10 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 24 |
| 24°F | May 8 | May 3 | Apr 30 | Apr 27 | Apr 25 | Apr 23 | Apr 20 | Apr 16 | Apr 12 |
| 20°F | Apr 27 | Apr 23 | Apr 19 | Apr 16 | Apr 13 | Apr 11 | Apr 7 | Apr 4 | Mar 31 |
| 16°F | Apr 19 | Apr 14 | Apr 10 | Apr 6 | Apr 4 | Apr 2 | Mar 31 | Mar 29 | Mar 24 |
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) | Aug 29 | Sep 16 | Oct 2 |
| Freeze (32°F) | Sep 14 | Oct 1 | Oct 16 |
| Hard (28°F) | Sep 26 | Oct 14 | Oct 31 |
| Severe (24°F) | Oct 15 | Oct 31 | Nov 13 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 29 | Sep 4 | Sep 9 | Sep 13 | Sep 16 | Sep 19 | Sep 23 | Sep 27 | Oct 2 |
| 32°F | Sep 14 | Sep 20 | Sep 23 | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 16 |
| 28°F | Sep 26 | Oct 2 | Oct 7 | Oct 10 | Oct 14 | Oct 17 | Oct 21 | Oct 26 | Oct 31 |
| 24°F | Oct 15 | Oct 21 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 13 |
| 20°F | Oct 30 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 14 | Nov 17 | Nov 20 | Nov 23 |
| 16°F | Nov 7 | Nov 13 | Nov 16 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Dec 1 | Dec 6 |
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: Greenland 6N, Mi, about 9.7 miles away@if(!empty($station['elevation_ft'])), at 791 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 Mass City, MI?
On average, the last spring frost (32°F) around Mass City, MI is about May 23. In cooler years it can run later, so for a safer bet many gardeners wait until May 6.
When is the first frost in the fall?
The first fall frost around Mass City, MI typically arrives about Oct 1. 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 23 on average, or May 6 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 128 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 49948 Planting calendar → Michigan frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026