Frost dates for 56737Middle River, MN
The average last spring frost in Middle River is May 20 and the average first fall frost is September 17, giving a typical growing season of about 118 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Sep 17
- Growing season
- 118 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 1 (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 · Jun 1 · Jun 21 | Aug 15 · Sep 5 · Sep 20 | 93 days | 100% |
| Frost / freeze (32°F) | May 5 · May 20 · Jun 3 | Sep 1 · Sep 17 · Oct 2 | 118 days | 100% |
| Hard freeze (28°F) | Apr 24 · May 8 · May 24 | Sep 11 · Sep 28 · Oct 13 | 142 days | 100% |
Planting calendar for Middle River
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 – May 28 |
| 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 7 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jun 30 |
| Sweet corn | Sow outdoors | Jun 5 – May 28 |
| 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) | May 18 – May 28 |
| Broccoli | Transplant outdoors (fall) | Jun 17 – Jun 28 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 8 – Jun 7 |
| Cabbage | Transplant outdoors (fall) | Jun 7 – Jul 8 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 7 – Jul 24 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jun 24 – Jul 29 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 7 – Aug 8 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | May 31 – Jul 8 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 8 – Jun 23 |
| Garlic | Plant outdoors (fall) | Sep 7 – Oct 8 |
Where these dates come from
ZIP code 56737 is matched to the NOAA station Goodridge 12 Nnw, MN, 23.9 km away, at 1,150 ft elevation (2 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Goodridge 12 Nnw, MN (used) | 1,150 ft | May 20 | Sep 17 |
| Agassiz Refuge, MN | 1,142 ft | May 6 | Oct 3 |
| Thief Rvr Falls 2, MN | 1,128 ft | May 14 | Sep 28 |
| Argyle, MN | 847 ft | May 15 | Sep 26 |
Frost dates near Middle River
- Strathcona, MN 56759 · last May 20, first Sep 17
- Newfolden, MN 56738 · last May 14, first Sep 28
- Gatzke, MN 56724 · last May 20, first Sep 17
- Strandquist, MN 56758 · last May 15, first Sep 26
- Greenbush, MN 56726 · last May 20, first Sep 17
- Viking, MN 56760 · last May 14, first Sep 28
- Karlstad, MN 56732 · last May 15, first Sep 26
- Thief River Falls, MN 56701 · last May 14, first Sep 28
Frequently asked questions
- When is the last frost in Middle River, MN?
- For ZIP code 56737, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Goodridge 12 Nnw, MN weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Middle River, MN?
- The average first fall frost (32°F) is September 17. There is a 1-in-10 chance of frost by September 1, so tender plants are at risk from that point on.
- How long is the growing season in 56737?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 118 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.