Frost dates for 51231Archer, IA
The average last spring frost in Archer is April 29 and the average first fall frost is October 10, giving a typical growing season of about 163 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 29
- Average first fall frost
- Oct 10
- Growing season
- 163 days
Safer after May 11 (1-in-10 risk)
Possible by Sep 26 (1-in-10 risk)
Last frost typically in 184 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 24 · May 8 · May 22 | Sep 19 · Oct 1 · Oct 14 | 146 days | 100% |
| Frost / freeze (32°F) | Apr 13 · Apr 29 · May 11 | Sep 26 · Oct 10 · Oct 23 | 163 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 18 · May 1 | Oct 5 · Oct 21 · Nov 4 | 185 days | 100% |
Planting calendar for Archer
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 | Mar 29 – Jun 4 |
| Tomatoes | Transplant outdoors | May 15 – Jun 20 |
| Peppers | Start seeds indoors | Mar 29 – Apr 29 |
| Peppers | Transplant outdoors | May 29 – Jun 29 |
| Eggplant | Start seeds indoors | Apr 15 – May 14 |
| Eggplant | Transplant outdoors | May 29 – Jun 29 |
| Cucumbers | Sow outdoors | May 29 – Jun 30 |
| Summer squash | Sow outdoors | May 15 – Jun 29 |
| Winter squash & pumpkins | Sow outdoors | May 29 – Jun 29 |
| Snap beans | Sow outdoors | May 15 – Jul 23 |
| Sweet corn | Sow outdoors | May 15 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | May 29 – Jun 29 |
| Okra | Sow outdoors | May 22 – Jun 14 |
| Peas | Sow outdoors (spring) | Mar 29 – May 14 |
| Potatoes | Plant outdoors (spring) | Mar 29 – May 29 |
| Onions | Start seeds indoors (spring) | Feb 15 – Mar 14 |
| Onions | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (spring) | Mar 11 – Apr 14 |
| Broccoli | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Mar 1 – Mar 29 |
| Cabbage | Transplant outdoors (spring) | Mar 29 – Apr 29 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Mar 29 – Jun 14 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 22 – May 5 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Mar 29 – May 19 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 15 – May 5 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | Apr 29 – Jun 14 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 51231 is matched to the NOAA station Primghar, IA, 9.8 km away, at 1,520 ft elevation (57 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Primghar, IA (used) | 1,520 ft | Apr 29 | Oct 10 |
| Sanborn, IA | 1,551 ft | May 1 | Oct 7 |
| Sheldon, IA | 1,420 ft | May 5 | Sep 28 |
| Sibley, IA | 1,529 ft | May 5 | Oct 3 |
Frost dates near Archer
- Primghar, IA 51245 · last Apr 29, first Oct 10
- Sanborn, IA 51248 · last May 1, first Oct 7
- Sheldon, IA 51201 · last May 5, first Sep 28
- Hospers, IA 51238 · last May 5, first Sep 28
- Paullina, IA 51046 · last Apr 29, first Oct 10
- Granville, IA 51022 · last May 5, first Sep 28
- Ashton, IA 51232 · last May 5, first Oct 3
- Matlock, IA 51244 · last May 5, first Sep 28
Frequently asked questions
- When is the last frost in Archer, IA?
- For ZIP code 51231, the average last spring frost (32°F) is April 29, based on NOAA 1991-2020 climate normals for the Primghar, IA weather station. There is a 1-in-10 chance of a frost after May 11.
- When is the first frost in Archer, IA?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 26, so tender plants are at risk from that point on.
- How long is the growing season in 51231?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 163 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.