Frost dates for 52302Marion, IA
The average last spring frost in Marion is April 28 and the average first fall frost is October 12, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 28
- Average first fall frost
- Oct 12
- Growing season
- 166 days
Safer after May 13 (1-in-10 risk)
Possible by Sep 29 (1-in-10 risk)
Last frost typically in 177 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 23 · May 7 · May 22 | Sep 19 · Oct 2 · Oct 14 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 28 · May 13 | Sep 29 · Oct 12 · Oct 25 | 166 days | 100% |
| Hard freeze (28°F) | Apr 4 · Apr 17 · May 2 | Oct 8 · Oct 22 · Nov 1 | 186 days | 100% |
Planting calendar for Marion
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 28 – Jun 3 |
| Tomatoes | Transplant outdoors | May 14 – Jun 22 |
| Peppers | Start seeds indoors | Mar 28 – Apr 28 |
| Peppers | Transplant outdoors | May 28 – Jun 28 |
| Eggplant | Start seeds indoors | Apr 14 – May 13 |
| Eggplant | Transplant outdoors | May 28 – Jun 28 |
| Cucumbers | Sow outdoors | May 28 – Jul 2 |
| Summer squash | Sow outdoors | May 14 – Jun 28 |
| Winter squash & pumpkins | Sow outdoors | May 28 – Jun 28 |
| Snap beans | Sow outdoors | May 14 – Jul 25 |
| Sweet corn | Sow outdoors | May 14 – Jun 22 |
| Watermelon & cantaloupe | Sow outdoors | May 28 – Jun 28 |
| Okra | Sow outdoors | May 21 – Jun 13 |
| Peas | Sow outdoors (spring) | Mar 28 – May 13 |
| Potatoes | Plant outdoors (spring) | Mar 28 – May 28 |
| Onions | Start seeds indoors (spring) | Feb 14 – Mar 13 |
| Onions | Transplant outdoors (spring) | Apr 14 – May 13 |
| Broccoli | Start seeds indoors (spring) | Mar 10 – Apr 13 |
| Broccoli | Transplant outdoors (spring) | Apr 14 – May 13 |
| Broccoli | Start seeds indoors (fall) | Jun 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Feb 28 – Mar 28 |
| Cabbage | Transplant outdoors (spring) | Mar 28 – Apr 28 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Mar 28 – Jun 13 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Mar 21 – May 4 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Mar 28 – May 18 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | Apr 14 – May 4 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | Apr 28 – Jun 13 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 52302 is matched to the NOAA station Cedar Rapids #1, IA, 1.1 km away, at 813 ft elevation (9 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Cedar Rapids #1, IA (used) | 813 ft | Apr 28 | Oct 12 |
| Cedar Rapids Muni Ap, IA | 868 ft | Apr 27 | Oct 11 |
| Anamosa 3 Ssw, IA | 906 ft | Apr 27 | Oct 13 |
| Anamosa 1 Wnw, IA | 805 ft | May 1 | Oct 4 |
Frost dates near Marion
- Cedar Rapids, IA 52407 · last Apr 28, first Oct 12
- Robins, IA 52328 · last Apr 28, first Oct 12
- Hiawatha, IA 52233 · last Apr 28, first Oct 12
- Springville, IA 52336 · last Apr 28, first Oct 12
- Toddville, IA 52341 · last Apr 28, first Oct 12
- Alburnett, IA 52202 · last May 3, first Oct 7
- Palo, IA 52324 · last Apr 28, first Oct 12
- Ely, IA 52227 · last Apr 27, first Oct 11
Frequently asked questions
- When is the last frost in Marion, IA?
- For ZIP code 52302, the average last spring frost (32°F) is April 28, based on NOAA 1991-2020 climate normals for the Cedar Rapids #1, IA weather station. There is a 1-in-10 chance of a frost after May 13.
- When is the first frost in Marion, IA?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 29, so tender plants are at risk from that point on.
- How long is the growing season in 52302?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 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.