Frost dates for 48139Hamburg, MI
The average last spring frost in Hamburg is May 5 and the average first fall frost is October 13, giving a typical growing season of about 160 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Oct 13
- Growing season
- 160 days
Safer after May 21 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 183 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) | May 1 · May 17 · May 31 | Sep 20 · Oct 1 · Oct 13 | 139 days | 100% |
| Frost / freeze (32°F) | Apr 22 · May 5 · May 21 | Sep 30 · Oct 13 · Oct 26 | 160 days | 100% |
| Hard freeze (28°F) | Apr 12 · Apr 26 · May 10 | Oct 12 · Oct 26 · Nov 7 | 184 days | 100% |
Planting calendar for Hamburg
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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 23 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jul 3 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 26 |
| Sweet corn | Sow outdoors | May 21 – Jun 23 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | Jun 13 – Jun 23 |
| Broccoli | Transplant outdoors (fall) | Jul 13 – Jul 24 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | Jun 3 – Jul 3 |
| Cabbage | Transplant outdoors (fall) | Jul 3 – Aug 3 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jul 3 – Aug 19 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 20 – Aug 24 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jul 3 – Sep 3 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 26 – Aug 3 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | Jun 3 – Jul 19 |
| Garlic | Plant outdoors (fall) | Oct 3 – Nov 3 |
Where these dates come from
ZIP code 48139 is matched to the NOAA station Whitmore Lake 1Nw, MI, 3.2 km away, at 906 ft elevation (46 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Whitmore Lake 1Nw, MI (used) | 906 ft | May 5 | Oct 13 |
| Hell, MI | 890 ft | Apr 30 | Oct 14 |
| Milford Gm Proving Ground, MI | 970 ft | May 6 | Oct 12 |
| Howell Wwtp, MI | 917 ft | May 4 | Oct 7 |
Frost dates near Hamburg
- Lakeland, MI 48143 · last May 5, first Oct 13
- Whitmore Lake, MI 48189 · last May 5, first Oct 13
- Pinckney, MI 48169 · last Apr 30, first Oct 12
- Brighton, MI 48116 · last May 6, first Oct 12
- Dexter, MI 48130 · last Apr 30, first Oct 12
- South Lyon, MI 48178 · last May 6, first Oct 12
- New Hudson, MI 48165 · last May 6, first Oct 12
- Howell, MI 48844 · last May 4, first Oct 7
Frequently asked questions
- When is the last frost in Hamburg, MI?
- For ZIP code 48139, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Whitmore Lake 1Nw, MI weather station. There is a 1-in-10 chance of a frost after May 21.
- When is the first frost in Hamburg, MI?
- The average first fall frost (32°F) is October 13. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 48139?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 160 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.