Frost dates for 52101Decorah, IA
The average last spring frost in Decorah is May 3 and the average first fall frost is October 7, giving a typical growing season of about 157 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 3
- Average first fall frost
- Oct 7
- Growing season
- 157 days
Safer after May 16 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 188 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) | Apr 29 · May 13 · May 26 | Sep 15 · Sep 28 · Oct 10 | 138 days | 100% |
| Frost / freeze (32°F) | Apr 19 · May 3 · May 16 | Sep 25 · Oct 7 · Oct 21 | 157 days | 100% |
| Hard freeze (28°F) | Apr 7 · Apr 22 · May 8 | Oct 3 · Oct 17 · Oct 31 | 178 days | 100% |
Planting calendar for Decorah
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 2 – Jun 8 |
| Tomatoes | Transplant outdoors | May 19 – Jun 17 |
| Peppers | Start seeds indoors | Apr 2 – May 3 |
| Peppers | Transplant outdoors | Jun 2 – Jul 3 |
| Eggplant | Start seeds indoors | Apr 19 – May 18 |
| Eggplant | Transplant outdoors | Jun 2 – Jul 3 |
| Cucumbers | Sow outdoors | Jun 2 – Jun 27 |
| Summer squash | Sow outdoors | May 19 – Jul 3 |
| Winter squash & pumpkins | Sow outdoors | Jun 2 – Jul 3 |
| Snap beans | Sow outdoors | May 19 – Jul 20 |
| Sweet corn | Sow outdoors | May 19 – Jun 17 |
| Watermelon & cantaloupe | Sow outdoors | Jun 2 – Jul 3 |
| Okra | Sow outdoors | May 26 – Jun 18 |
| Peas | Sow outdoors (spring) | Apr 2 – May 18 |
| Potatoes | Plant outdoors (spring) | Apr 2 – Jun 2 |
| Onions | Start seeds indoors (spring) | Feb 19 – Mar 18 |
| Onions | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (spring) | Mar 15 – Apr 18 |
| Broccoli | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (fall) | Jun 7 – Jun 17 |
| Broccoli | Transplant outdoors (fall) | Jul 7 – Jul 18 |
| Cabbage | Start seeds indoors (spring) | Mar 5 – Apr 2 |
| Cabbage | Transplant outdoors (spring) | Apr 2 – May 3 |
| Cabbage | Start seeds indoors (fall) | May 28 – Jun 27 |
| Cabbage | Transplant outdoors (fall) | Jun 27 – Jul 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 2 – Jun 18 |
| Leaf lettuce | Sow outdoors (fall) | Jun 27 – Aug 13 |
| Spinach | Sow outdoors (spring) | Mar 26 – May 9 |
| Spinach | Sow outdoors (fall) | Jul 14 – Aug 18 |
| Radishes | Sow outdoors (spring) | Apr 2 – May 23 |
| Radishes | Sow outdoors (fall) | Jun 27 – Aug 28 |
| Kale | Sow outdoors (spring) | Apr 19 – May 9 |
| Kale | Sow outdoors (fall) | Jun 20 – Jul 28 |
| Carrots | Sow outdoors (spring) | May 3 – Jun 18 |
| Carrots | Sow outdoors (fall) | May 28 – Jul 13 |
| Garlic | Plant outdoors (fall) | Sep 27 – Oct 28 |
Where these dates come from
ZIP code 52101 is matched to the NOAA station Decorah, IA, 2.1 km away, at 860 ft elevation (302 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Decorah, IA (used) | 860 ft | May 3 | Oct 7 |
| Mabel, MN | 1,112 ft | May 10 | Sep 28 |
| Cresco 1 Ne, IA | 1,255 ft | May 8 | Oct 1 |
| Waukon, IA | 1,275 ft | May 2 | Oct 11 |
Frost dates near Decorah
- Calmar, IA 52132 · last May 8, first Oct 1
- Ridgeway, IA 52165 · last May 8, first Oct 1
- Highlandville, IA 52149 · last Apr 29, first Oct 10
- Spillville, IA 52168 · last May 3, first Oct 7
- Ossian, IA 52161 · last May 1, first Oct 3
- Fort Atkinson, IA 52144 · last May 3, first Oct 7
- Castalia, IA 52133 · last May 1, first Oct 3
- Mabel, MN 55954 · last May 10, first Sep 28
Frequently asked questions
- When is the last frost in Decorah, IA?
- For ZIP code 52101, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Decorah, IA weather station. There is a 1-in-10 chance of a frost after May 16.
- When is the first frost in Decorah, IA?
- The average first fall frost (32°F) is October 7. 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 52101?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 157 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.