Frost dates for 19810Wilmington, DE
The average last spring frost in Wilmington is April 7 and the average first fall frost is November 4, giving a typical growing season of about 209 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 7
- Average first fall frost
- Nov 4
- Growing season
- 209 days
Safer after Apr 24 (1-in-10 risk)
Possible by Oct 21 (1-in-10 risk)
First frost typically in 1 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 6 · Apr 20 · May 7 | Oct 9 · Oct 24 · Nov 6 | 185 days | 100% |
| Frost / freeze (32°F) | Mar 26 · Apr 7 · Apr 24 | Oct 21 · Nov 4 · Nov 19 | 209 days | 100% |
| Hard freeze (28°F) | Mar 13 · Mar 29 · Apr 10 | Nov 1 · Nov 15 · Dec 2 | 232 days | 100% |
Planting calendar for Wilmington
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 7 – May 13 |
| Tomatoes | Transplant outdoors | Apr 23 – Jul 15 |
| Peppers | Start seeds indoors | Mar 7 – Apr 7 |
| Peppers | Transplant outdoors | May 7 – Jun 7 |
| Eggplant | Start seeds indoors | Mar 24 – Apr 22 |
| Eggplant | Transplant outdoors | May 7 – Jun 7 |
| Cucumbers | Sow outdoors | May 7 – Jul 25 |
| Summer squash | Sow outdoors | Apr 23 – Jun 7 |
| Winter squash & pumpkins | Sow outdoors | May 7 – Jun 7 |
| Snap beans | Sow outdoors | Apr 23 – Aug 17 |
| Sweet corn | Sow outdoors | Apr 23 – Jul 15 |
| Watermelon & cantaloupe | Sow outdoors | May 7 – Jun 7 |
| Okra | Sow outdoors | Apr 30 – May 23 |
| Peas | Sow outdoors (spring) | Mar 7 – Apr 22 |
| Potatoes | Plant outdoors (spring) | Mar 7 – May 7 |
| Onions | Start seeds indoors (spring) | Jan 24 – Feb 20 |
| Onions | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (spring) | Feb 17 – Mar 23 |
| Broccoli | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (fall) | Jul 5 – Jul 15 |
| Broccoli | Transplant outdoors (fall) | Aug 4 – Aug 15 |
| Cabbage | Start seeds indoors (spring) | Feb 7 – Mar 7 |
| Cabbage | Transplant outdoors (spring) | Mar 7 – Apr 7 |
| Cabbage | Start seeds indoors (fall) | Jun 25 – Jul 25 |
| Cabbage | Transplant outdoors (fall) | Jul 25 – Aug 25 |
| Leaf lettuce | Sow outdoors (spring) | Mar 7 – May 23 |
| Leaf lettuce | Sow outdoors (fall) | Jul 25 – Sep 10 |
| Spinach | Sow outdoors (spring) | Feb 28 – Apr 13 |
| Spinach | Sow outdoors (fall) | Aug 11 – Sep 15 |
| Radishes | Sow outdoors (spring) | Mar 7 – Apr 27 |
| Radishes | Sow outdoors (fall) | Jul 25 – Sep 25 |
| Kale | Sow outdoors (spring) | Mar 24 – Apr 13 |
| Kale | Sow outdoors (fall) | Jul 18 – Aug 25 |
| Carrots | Sow outdoors (spring) | Apr 7 – May 23 |
| Carrots | Sow outdoors (fall) | Jun 25 – Aug 10 |
| Garlic | Plant outdoors (fall) | Oct 25 – Nov 25 |
Where these dates come from
ZIP code 19810 is matched to the NOAA station Wilmington Porter Rsch, DE, 5.8 km away, at 270 ft elevation (55 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Wilmington Porter Rsch, DE (used) | 270 ft | Apr 7 | Nov 4 |
| Marcus Hook, PA | 10 ft | Mar 30 | Nov 16 |
| Wilmington New Castle Co Ap, DE | 79 ft | Apr 7 | Nov 1 |
| W Chester 2 Nw, PA | 375 ft | Apr 26 | Oct 18 |
Frost dates near Wilmington
- Wilmington, DE 19803 · last Apr 7, first Nov 4
- Garnet Valley, PA 19060 · last Apr 7, first Nov 4
- Claymont, DE 19703 · last Mar 30, first Nov 16
- Marcus Hook, PA 19061 · last Mar 30, first Nov 16
- Rockland, DE 19732 · last Apr 7, first Nov 4
- Concordville, PA 19331 · last Apr 7, first Nov 4
- Winterthur, DE 19735 · last Apr 7, first Nov 4
- Montchanin, DE 19710 · last Apr 7, first Nov 4
Frequently asked questions
- When is the last frost in Wilmington, DE?
- For ZIP code 19810, the average last spring frost (32°F) is April 7, based on NOAA 1991-2020 climate normals for the Wilmington Porter Rsch, DE weather station. There is a 1-in-10 chance of a frost after April 24.
- When is the first frost in Wilmington, DE?
- The average first fall frost (32°F) is November 4. There is a 1-in-10 chance of frost by October 21, so tender plants are at risk from that point on.
- How long is the growing season in 19810?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 209 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.