Frost dates for 48480Grand Blanc, MI
The average last spring frost in Grand Blanc is May 1 and the average first fall frost is October 14, giving a typical growing season of about 164 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 1
- Average first fall frost
- Oct 14
- Growing season
- 164 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 180 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 29 · May 11 · May 28 | Sep 20 · Oct 2 · Oct 14 | 142 days | 100% |
| Frost / freeze (32°F) | Apr 20 · May 1 · May 18 | Sep 30 · Oct 14 · Oct 28 | 164 days | 100% |
| Hard freeze (28°F) | Apr 10 · Apr 22 · May 6 | Oct 13 · Oct 28 · Nov 11 | 187 days | 100% |
Planting calendar for Grand Blanc
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 | Mar 31 – Jun 6 |
| Tomatoes | Transplant outdoors | May 17 – Jun 24 |
| Peppers | Start seeds indoors | Mar 31 – May 1 |
| Peppers | Transplant outdoors | May 31 – Jul 1 |
| Eggplant | Start seeds indoors | Apr 17 – May 16 |
| Eggplant | Transplant outdoors | May 31 – Jul 1 |
| Cucumbers | Sow outdoors | May 31 – Jul 4 |
| Summer squash | Sow outdoors | May 17 – Jul 1 |
| Winter squash & pumpkins | Sow outdoors | May 31 – Jul 1 |
| Snap beans | Sow outdoors | May 17 – Jul 27 |
| Sweet corn | Sow outdoors | May 17 – Jun 24 |
| Watermelon & cantaloupe | Sow outdoors | May 31 – Jul 1 |
| Okra | Sow outdoors | May 24 – Jun 16 |
| Peas | Sow outdoors (spring) | Mar 31 – May 16 |
| Potatoes | Plant outdoors (spring) | Mar 31 – May 31 |
| Onions | Start seeds indoors (spring) | Feb 17 – Mar 16 |
| Onions | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (spring) | Mar 13 – Apr 16 |
| Broccoli | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (fall) | Jun 14 – Jun 24 |
| Broccoli | Transplant outdoors (fall) | Jul 14 – Jul 25 |
| Cabbage | Start seeds indoors (spring) | Mar 3 – Mar 31 |
| Cabbage | Transplant outdoors (spring) | Mar 31 – May 1 |
| Cabbage | Start seeds indoors (fall) | Jun 4 – Jul 4 |
| Cabbage | Transplant outdoors (fall) | Jul 4 – Aug 4 |
| Leaf lettuce | Sow outdoors (spring) | Mar 31 – Jun 16 |
| Leaf lettuce | Sow outdoors (fall) | Jul 4 – Aug 20 |
| Spinach | Sow outdoors (spring) | Mar 24 – May 7 |
| Spinach | Sow outdoors (fall) | Jul 21 – Aug 25 |
| Radishes | Sow outdoors (spring) | Mar 31 – May 21 |
| Radishes | Sow outdoors (fall) | Jul 4 – Sep 4 |
| Kale | Sow outdoors (spring) | Apr 17 – May 7 |
| Kale | Sow outdoors (fall) | Jun 27 – Aug 4 |
| Carrots | Sow outdoors (spring) | May 1 – Jun 16 |
| Carrots | Sow outdoors (fall) | Jun 4 – Jul 20 |
| Garlic | Plant outdoors (fall) | Oct 4 – Nov 4 |
Where these dates come from
ZIP code 48480 is matched to the NOAA station Goodrich, MI, 8.7 km away, at 910 ft elevation (60 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Goodrich, MI (used) | 910 ft | May 1 | Oct 14 |
| Flint Bishop Intl Ap, MI | 770 ft | May 6 | Oct 10 |
| Burton 4N, MI | 757 ft | May 8 | Oct 5 |
| Flint 7W, MI | 679 ft | May 3 | Oct 13 |
Frost dates near Grand Blanc
- Grand Blanc, MI 48439 · last May 1, first Oct 14
- Atlas, MI 48411 · last May 1, first Oct 14
- Burton, MI 48529 · last May 6, first Oct 10
- Flint, MI 48552 · last May 6, first Oct 10
- Goodrich, MI 48438 · last May 1, first Oct 14
- Holly, MI 48442 · last May 1, first Oct 14
- Davison, MI 48423 · last May 1, first Oct 14
- Swartz Creek, MI 48473 · last May 6, first Oct 10
Frequently asked questions
- When is the last frost in Grand Blanc, MI?
- For ZIP code 48480, the average last spring frost (32°F) is May 1, based on NOAA 1991-2020 climate normals for the Goodrich, MI weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Grand Blanc, MI?
- The average first fall frost (32°F) is October 14. 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 48480?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 164 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.