Frost dates for 48625Harrison, MI
The average last spring frost in Harrison is May 30 and the average first fall frost is September 15, giving a typical growing season of about 106 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 30
- Average first fall frost
- Sep 15
- Growing season
- 106 days
Safer after Jun 19 (1-in-10 risk)
Possible by Aug 26 (1-in-10 risk)
Last frost typically in 209 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) | — | — | 76 days | 100% |
| Frost / freeze (32°F) | May 12 · May 30 · Jun 19 | Aug 26 · Sep 15 · Oct 1 | 106 days | 100% |
| Hard freeze (28°F) | Apr 28 · May 16 · May 31 | Sep 13 · Sep 30 · Oct 17 | 136 days | 100% |
Planting calendar for Harrison
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 29 – Jul 5 |
| Tomatoes | Transplant outdoors | Jun 15 – May 26 |
| Peppers | Start seeds indoors | Apr 29 – May 30 |
| Peppers | Transplant outdoors | Jun 29 – Jul 30 |
| Eggplant | Start seeds indoors | May 16 – Jun 14 |
| Eggplant | Transplant outdoors | Jun 29 – Jul 30 |
| Cucumbers | Sow outdoors | Jun 29 – Jun 5 |
| Summer squash | Sow outdoors | Jun 15 – Jul 30 |
| Winter squash & pumpkins | Sow outdoors | Jun 29 – Jul 30 |
| Snap beans | Sow outdoors | Jun 15 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 15 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jun 29 – Jul 30 |
| Okra | Sow outdoors | Jun 22 – Jul 15 |
| Peas | Sow outdoors (spring) | Apr 29 – Jun 14 |
| Potatoes | Plant outdoors (spring) | Apr 29 – Jun 29 |
| Onions | Start seeds indoors (spring) | Mar 18 – Apr 14 |
| Onions | Transplant outdoors (spring) | May 16 – Jun 14 |
| Broccoli | Start seeds indoors (spring) | Apr 11 – May 15 |
| Broccoli | Transplant outdoors (spring) | May 16 – Jun 14 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Apr 1 – Apr 29 |
| Cabbage | Transplant outdoors (spring) | Apr 29 – May 30 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | Apr 29 – Jul 15 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 22 – Jun 5 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | Apr 29 – Jun 19 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 16 – Jun 5 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | May 30 – Jul 15 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 48625 is matched to the NOAA station Houghton Lake 6 Wsw, MI, 32.9 km away, at 1,135 ft elevation (6 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Houghton Lake 6 Wsw, MI (used) | 1,135 ft | May 30 | Sep 15 |
| Gladwin, MI | 775 ft | May 9 | Oct 4 |
| Houghton Lake 2Nw, MI | 1,161 ft | May 20 | Oct 1 |
| Houghton Lk Roscommon Ap, MI | 1,151 ft | May 19 | Sep 23 |
Frost dates near Harrison
- Lake George, MI 48633 · last May 30, first Sep 15
- Gladwin, MI 48624 · last May 9, first Oct 4
- Clare, MI 48617 · last Apr 30, first Oct 20
- Farwell, MI 48622 · last Apr 30, first Oct 20
- Lake, MI 48632 · last May 13, first Oct 2
- Marion, MI 49665 · last May 22, first Sep 26
- Prudenville, MI 48651 · last May 19, first Sep 23
- Falmouth, MI 49632 · last May 30, first Sep 15
Frequently asked questions
- When is the last frost in Harrison, MI?
- For ZIP code 48625, the average last spring frost (32°F) is May 30, based on NOAA 1991-2020 climate normals for the Houghton Lake 6 Wsw, MI weather station. There is a 1-in-10 chance of a frost after June 19.
- When is the first frost in Harrison, MI?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by August 26, so tender plants are at risk from that point on.
- How long is the growing season in 48625?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 106 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.