Last spring frost
May 3
Frost Dates for Byron, MI
First fall frost
Oct 12
Growing season
161 days
Hardiness zone
6a
In an average year around Byron, MI, the last spring frost (32°F) is about May 3 and the first fall frost is about Oct 12, giving roughly a 161-day growing season. To be safe most years, wait until Apr 21 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) | May 30 | May 15 | Apr 30 |
| Freeze (32°F) | May 20 | May 3 | Apr 21 |
| Hard (28°F) | May 9 | Apr 23 | Apr 10 |
| Severe (24°F) | Apr 23 | Apr 11 | Mar 31 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 30 | May 25 | May 22 | May 18 | May 15 | May 11 | May 7 | May 3 | Apr 30 |
| 32°F | May 20 | May 15 | May 10 | May 5 | May 3 | Apr 30 | Apr 28 | Apr 24 | Apr 21 |
| 28°F | May 9 | May 2 | Apr 29 | Apr 26 | Apr 23 | Apr 20 | Apr 17 | Apr 14 | Apr 10 |
| 24°F | Apr 23 | Apr 19 | Apr 16 | Apr 13 | Apr 11 | Apr 8 | Apr 5 | Apr 2 | Mar 31 |
| 20°F | Apr 14 | Apr 7 | Apr 4 | Apr 2 | Mar 31 | Mar 29 | Mar 25 | Mar 21 | Mar 16 |
| 16°F | Apr 3 | Mar 31 | Mar 27 | Mar 24 | Mar 21 | Mar 18 | Mar 16 | Mar 13 | Mar 7 |
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 20 | Oct 1 | Oct 13 |
| Freeze (32°F) | Sep 30 | Oct 12 | Oct 28 |
| Hard (28°F) | Oct 10 | Oct 27 | Nov 9 |
| Severe (24°F) | Oct 24 | Nov 7 | Nov 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 13 |
| 32°F | Sep 30 | Oct 3 | Oct 7 | Oct 10 | Oct 12 | Oct 15 | Oct 19 | Oct 22 | Oct 28 |
| 28°F | Oct 10 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 9 |
| 24°F | Oct 24 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 17 | Nov 24 |
| 20°F | Nov 5 | Nov 9 | Nov 14 | Nov 18 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 7 |
| 16°F | Nov 15 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 19 |
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: Linden Wwtp, Mi, about 8.4 miles away@if(!empty($station['elevation_ft'])), at 863 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 Byron, MI?
On average, the last spring frost (32°F) around Byron, MI is about May 3. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 21.
When is the first frost in the fall?
The first fall frost around Byron, MI typically arrives about Oct 12. 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 3 on average, or Apr 21 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 161 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 48816 Planting calendar → Michigan frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026