Frost dates for 49839Grand Marais, MI
The average last spring frost in Grand Marais is May 27 and the average first fall frost is October 10, giving a typical growing season of about 138 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 27
- Average first fall frost
- Oct 10
- Growing season
- 138 days
Safer after Jun 13 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 213 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 26 · Jun 10 · Jul 6 | Sep 5 · Sep 29 · Oct 12 | 107 days | 100% |
| Frost / freeze (32°F) | May 7 · May 27 · Jun 13 | Sep 25 · Oct 10 · Oct 27 | 138 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 9 · May 27 | Oct 7 · Oct 25 · Nov 8 | 168 days | 100% |
Planting calendar for Grand Marais
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 26 – Jul 2 |
| Tomatoes | Transplant outdoors | Jun 12 – Jun 20 |
| Peppers | Start seeds indoors | Apr 26 – May 27 |
| Peppers | Transplant outdoors | Jun 26 – Jul 27 |
| Eggplant | Start seeds indoors | May 13 – Jun 11 |
| Eggplant | Transplant outdoors | Jun 26 – Jul 27 |
| Cucumbers | Sow outdoors | Jun 26 – Jun 30 |
| Summer squash | Sow outdoors | Jun 12 – Jul 27 |
| Winter squash & pumpkins | Sow outdoors | Jun 26 – Jul 27 |
| Snap beans | Sow outdoors | Jun 12 – Jul 23 |
| Sweet corn | Sow outdoors | Jun 12 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | Jun 26 – Jul 27 |
| Okra | Sow outdoors | Jun 19 – Jul 12 |
| Peas | Sow outdoors (spring) | Apr 26 – Jun 11 |
| Potatoes | Plant outdoors (spring) | Apr 26 – Jun 26 |
| Onions | Start seeds indoors (spring) | Mar 15 – Apr 11 |
| Onions | Transplant outdoors (spring) | May 13 – Jun 11 |
| Broccoli | Start seeds indoors (spring) | Apr 8 – May 12 |
| Broccoli | Transplant outdoors (spring) | May 13 – Jun 11 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Mar 29 – Apr 26 |
| Cabbage | Transplant outdoors (spring) | Apr 26 – May 27 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Apr 26 – Jul 12 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Apr 19 – Jun 2 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Apr 26 – Jun 16 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | May 13 – Jun 2 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | May 27 – Jul 12 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 49839 is matched to the NOAA station Grand Marais 2 E, MI, 3 km away, at 624 ft elevation (213 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grand Marais 2 E, MI (used) | 624 ft | May 27 | Oct 10 |
| Newberry Correctional Facility, MI | 886 ft | May 21 | Oct 5 |
| Munsing Lakeshore, MI | 612 ft | May 23 | Oct 10 |
| Tahquamenon Falls Sp, MI | 745 ft | — | — |
Frost dates near Grand Marais
- Seney, MI 49883 · last May 27, first Oct 10
- Mc Millan, MI 49853 · last May 21, first Oct 5
- Germfask, MI 49836 · last May 21, first Oct 5
- Newberry, MI 49868 · last May 21, first Oct 5
- Shingleton, MI 49884 · last May 16, first Oct 14
- Curtis, MI 49820 · last May 21, first Oct 5
- Engadine, MI 49827 · last May 21, first Oct 5
- Wetmore, MI 49895 · last May 16, first Oct 14
Frequently asked questions
- When is the last frost in Grand Marais, MI?
- For ZIP code 49839, the average last spring frost (32°F) is May 27, based on NOAA 1991-2020 climate normals for the Grand Marais 2 E, MI weather station. There is a 1-in-10 chance of a frost after June 13.
- When is the first frost in Grand Marais, MI?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 25, so tender plants are at risk from that point on.
- How long is the growing season in 49839?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 138 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.