Frost dates for 48178South Lyon, MI
The average last spring frost in South Lyon is May 6 and the average first fall frost is October 12, giving a typical growing season of about 157 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 6
- Average first fall frost
- Oct 12
- Growing season
- 157 days
Safer after May 22 (1-in-10 risk)
Possible by Sep 27 (1-in-10 risk)
Last frost typically in 185 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 30 · May 18 · May 31 | Sep 19 · Oct 1 · Oct 15 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 6 · May 22 | Sep 27 · Oct 12 · Oct 27 | 157 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 26 · May 11 | Oct 8 · Oct 24 · Nov 6 | 179 days | 100% |
Planting calendar for South Lyon
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 5 – Jun 11 |
| Tomatoes | Transplant outdoors | May 22 – Jun 22 |
| Peppers | Start seeds indoors | Apr 5 – May 6 |
| Peppers | Transplant outdoors | Jun 5 – Jul 6 |
| Eggplant | Start seeds indoors | Apr 22 – May 21 |
| Eggplant | Transplant outdoors | Jun 5 – Jul 6 |
| Cucumbers | Sow outdoors | Jun 5 – Jul 2 |
| Summer squash | Sow outdoors | May 22 – Jul 6 |
| Winter squash & pumpkins | Sow outdoors | Jun 5 – Jul 6 |
| Snap beans | Sow outdoors | May 22 – Jul 25 |
| Sweet corn | Sow outdoors | May 22 – Jun 22 |
| Watermelon & cantaloupe | Sow outdoors | Jun 5 – Jul 6 |
| Okra | Sow outdoors | May 29 – Jun 21 |
| Peas | Sow outdoors (spring) | Apr 5 – May 21 |
| Potatoes | Plant outdoors (spring) | Apr 5 – Jun 5 |
| Onions | Start seeds indoors (spring) | Feb 22 – Mar 21 |
| Onions | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (spring) | Mar 18 – Apr 21 |
| Broccoli | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (fall) | Jun 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Mar 8 – Apr 5 |
| Cabbage | Transplant outdoors (spring) | Apr 5 – May 6 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Apr 5 – Jun 21 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Mar 29 – May 12 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Apr 5 – May 26 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | Apr 22 – May 12 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | May 6 – Jun 21 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 48178 is matched to the NOAA station Milford Gm Proving Ground, MI, 13.8 km away, at 970 ft elevation (52 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Milford Gm Proving Ground, MI (used) | 970 ft | May 6 | Oct 12 |
| Whitmore Lake 1Nw, MI | 906 ft | May 5 | Oct 13 |
| Ann Arbor U Of Mich, MI | 813 ft | May 3 | Oct 13 |
| Ann Arbor Se, MI | 832 ft | May 5 | Oct 10 |
Frost dates near South Lyon
- New Hudson, MI 48165 · last May 6, first Oct 12
- Salem, MI 48175 · last May 3, first Oct 13
- Whitmore Lake, MI 48189 · last May 5, first Oct 13
- Novi, MI 48374 · last May 6, first Oct 12
- Hamburg, MI 48139 · last May 5, first Oct 13
- Brighton, MI 48116 · last May 6, first Oct 12
- Wixom, MI 48393 · last May 6, first Oct 12
- Northville, MI 48168 · last May 1, first Oct 17
Frequently asked questions
- When is the last frost in South Lyon, MI?
- For ZIP code 48178, the average last spring frost (32°F) is May 6, based on NOAA 1991-2020 climate normals for the Milford Gm Proving Ground, MI weather station. There is a 1-in-10 chance of a frost after May 22.
- When is the first frost in South Lyon, MI?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 27, so tender plants are at risk from that point on.
- How long is the growing season in 48178?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 157 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.