Frost dates for 54855Marengo, WI
The average last spring frost in Marengo is May 23 and the average first fall frost is September 29, giving a typical growing season of about 125 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 23
- Average first fall frost
- Sep 29
- Growing season
- 125 days
Safer after Jun 6 (1-in-10 risk)
Possible by Sep 14 (1-in-10 risk)
Last frost typically in 208 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 23 · Jun 4 · Jun 18 | Sep 1 · Sep 17 · Oct 1 | 102 days | 100% |
| Frost / freeze (32°F) | May 8 · May 23 · Jun 6 | Sep 14 · Sep 29 · Oct 11 | 125 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 8 · May 23 | Sep 25 · Oct 9 · Oct 24 | 152 days | 100% |
Planting calendar for Marengo
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 22 – Jun 28 |
| Tomatoes | Transplant outdoors | Jun 8 – Jun 9 |
| Peppers | Start seeds indoors | Apr 22 – May 23 |
| Peppers | Transplant outdoors | Jun 22 – Jul 23 |
| Eggplant | Start seeds indoors | May 9 – Jun 7 |
| Eggplant | Transplant outdoors | Jun 22 – Jul 23 |
| Cucumbers | Sow outdoors | Jun 22 – Jun 19 |
| Summer squash | Sow outdoors | Jun 8 – Jul 23 |
| Winter squash & pumpkins | Sow outdoors | Jun 22 – Jul 23 |
| Snap beans | Sow outdoors | Jun 8 – Jul 12 |
| Sweet corn | Sow outdoors | Jun 8 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 22 – Jul 23 |
| Okra | Sow outdoors | Jun 15 – Jul 8 |
| Peas | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Potatoes | Plant outdoors (spring) | Apr 22 – Jun 22 |
| Onions | Start seeds indoors (spring) | Mar 11 – Apr 7 |
| Onions | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (spring) | Apr 4 – May 8 |
| Broccoli | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 25 – Apr 22 |
| Cabbage | Transplant outdoors (spring) | Apr 22 – May 23 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 22 – Jul 8 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Apr 15 – May 29 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 22 – Jun 12 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | May 9 – May 29 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 23 – Jul 8 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 54855 is matched to the NOAA station Ashland Kennedy Mem Ap, WI, 16.9 km away, at 826 ft elevation (14 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ashland Kennedy Mem Ap, WI (used) | 826 ft | May 23 | Sep 29 |
| Mellen 4 Ne, WI | 1,300 ft | May 26 | Sep 27 |
| Ashland 3S, WI | 826 ft | May 20 | Oct 2 |
| Clam Lake 4W, WI | 1,498 ft | May 16 | Sep 30 |
Frost dates near Marengo
- High Bridge, WI 54846 · last May 26, first Sep 27
- Mellen, WI 54546 · last May 26, first Sep 27
- Ashland, WI 54806 · last May 20, first Oct 2
- Benoit, WI 54816 · last May 23, first Sep 29
- Grand View, WI 54839 · last May 20, first Oct 1
- Mason, WI 54856 · last May 23, first Sep 29
- Odanah, WI 54861 · last May 20, first Oct 2
- Clam Lake, WI 54517 · last May 16, first Sep 30
Frequently asked questions
- When is the last frost in Marengo, WI?
- For ZIP code 54855, the average last spring frost (32°F) is May 23, based on NOAA 1991-2020 climate normals for the Ashland Kennedy Mem Ap, WI weather station. There is a 1-in-10 chance of a frost after June 6.
- When is the first frost in Marengo, WI?
- The average first fall frost (32°F) is September 29. There is a 1-in-10 chance of frost by September 14, so tender plants are at risk from that point on.
- How long is the growing season in 54855?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 125 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.