Frost dates for 49911Bessemer, MI
The average last spring frost in Bessemer is May 20 and the average first fall frost is October 1, giving a typical growing season of about 132 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Oct 1
- Growing season
- 132 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 17 (1-in-10 risk)
Last frost typically in 205 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 17 · May 31 · Jun 14 | Sep 5 · Sep 20 · Oct 3 | 109 days | 100% |
| Frost / freeze (32°F) | May 2 · May 20 · Jun 3 | Sep 17 · Oct 1 · Oct 15 | 132 days | 100% |
| Hard freeze (28°F) | Apr 22 · May 6 · May 23 | Sep 28 · Oct 12 · Oct 28 | 157 days | 100% |
Planting calendar for Bessemer
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 19 – Jun 25 |
| Tomatoes | Transplant outdoors | Jun 5 – Jun 11 |
| Peppers | Start seeds indoors | Apr 19 – May 20 |
| Peppers | Transplant outdoors | Jun 19 – Jul 20 |
| Eggplant | Start seeds indoors | May 6 – Jun 4 |
| Eggplant | Transplant outdoors | Jun 19 – Jul 20 |
| Cucumbers | Sow outdoors | Jun 19 – Jun 21 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jul 14 |
| Sweet corn | Sow outdoors | Jun 5 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 19 – Jul 20 |
| Okra | Sow outdoors | Jun 12 – Jul 5 |
| Peas | Sow outdoors (spring) | Apr 19 – Jun 4 |
| Potatoes | Plant outdoors (spring) | Apr 19 – Jun 19 |
| Onions | Start seeds indoors (spring) | Mar 8 – Apr 4 |
| Onions | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (spring) | Apr 1 – May 5 |
| Broccoli | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 49911 is matched to the NOAA station Ironwood, MI, 10.7 km away, at 1,430 ft elevation (10 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ironwood, MI (used) | 1,430 ft | May 20 | Oct 1 |
| Ironwood #2, MI | 1,520 ft | May 19 | Sep 28 |
| Hurley, WI | 1,444 ft | May 24 | Sep 28 |
| Saxon 1Wsw, WI | 1,165 ft | May 23 | Oct 1 |
Frost dates near Bessemer
- Ramsay, MI 49959 · last May 20, first Oct 1
- Wakefield, MI 49968 · last May 24, first Sep 28
- Ironwood, MI 49938 · last May 24, first Sep 28
- Hurley, WI 54534 · last May 24, first Sep 28
- Gile, WI 54525 · last May 24, first Sep 28
- Montreal, WI 54550 · last May 24, first Sep 28
- Iron Belt, WI 54536 · last May 24, first Sep 28
- Upson, WI 54565 · last May 24, first Sep 28
Frequently asked questions
- When is the last frost in Bessemer, MI?
- For ZIP code 49911, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Ironwood, MI weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Bessemer, MI?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 17, so tender plants are at risk from that point on.
- How long is the growing season in 49911?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 132 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.