Frost dates for 51201Sheldon, IA
The average last spring frost in Sheldon is May 5 and the average first fall frost is September 28, giving a typical growing season of about 145 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Sep 28
- Growing season
- 145 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 14 (1-in-10 risk)
Last frost typically in 190 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 1 · May 13 · May 25 | Sep 8 · Sep 20 · Oct 4 | 130 days | 100% |
| Frost / freeze (32°F) | Apr 24 · May 5 · May 18 | Sep 14 · Sep 28 · Oct 12 | 145 days | 100% |
| Hard freeze (28°F) | Apr 15 · Apr 28 · May 9 | Sep 23 · Oct 6 · Oct 21 | 161 days | 100% |
Planting calendar for Sheldon
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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 8 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jun 18 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 11 |
| Sweet corn | Sow outdoors | May 21 – Jun 8 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | May 29 – Jun 8 |
| Broccoli | Transplant outdoors (fall) | Jun 28 – Jul 9 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | May 19 – Jun 18 |
| Cabbage | Transplant outdoors (fall) | Jun 18 – Jul 19 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 18 – Aug 4 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 5 – Aug 9 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jun 18 – Aug 19 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 11 – Jul 19 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | May 19 – Jul 4 |
| Garlic | Plant outdoors (fall) | Sep 18 – Oct 19 |
Where these dates come from
ZIP code 51201 is matched to the NOAA station Sheldon, IA, 1.1 km away, at 1,420 ft elevation (24 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sheldon, IA (used) | 1,420 ft | May 5 | Sep 28 |
| Sanborn, IA | 1,551 ft | May 1 | Oct 7 |
| Primghar, IA | 1,520 ft | Apr 29 | Oct 10 |
| Sibley, IA | 1,529 ft | May 5 | Oct 3 |
Frost dates near Sheldon
- Matlock, IA 51244 · last May 5, first Sep 28
- Archer, IA 51231 · last Apr 29, first Oct 10
- Boyden, IA 51234 · last May 5, first Sep 28
- Hospers, IA 51238 · last May 5, first Sep 28
- Sanborn, IA 51248 · last May 1, first Oct 7
- Ashton, IA 51232 · last May 5, first Oct 3
- Primghar, IA 51245 · last Apr 29, first Oct 10
- George, IA 51237 · last May 1, first Oct 4
Frequently asked questions
- When is the last frost in Sheldon, IA?
- For ZIP code 51201, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Sheldon, IA weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Sheldon, IA?
- The average first fall frost (32°F) is September 28. 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 51201?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 145 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.