Frost dates for 18055Hellertown, PA
The average last spring frost in Hellertown is April 20 and the average first fall frost is October 24, giving a typical growing season of about 184 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 20
- Average first fall frost
- Oct 24
- Growing season
- 184 days
Safer after May 6 (1-in-10 risk)
Possible by Oct 8 (1-in-10 risk)
Last frost typically in 168 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 19 · May 2 · May 18 | Sep 29 · Oct 12 · Oct 28 | 161 days | 100% |
| Frost / freeze (32°F) | Apr 6 · Apr 20 · May 6 | Oct 8 · Oct 24 · Nov 6 | 184 days | 100% |
| Hard freeze (28°F) | Mar 23 · Apr 5 · Apr 18 | Oct 19 · Nov 4 · Nov 18 | 211 days | 100% |
Planting calendar for Hellertown
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 20 – May 26 |
| Tomatoes | Transplant outdoors | May 6 – Jul 4 |
| Peppers | Start seeds indoors | Mar 20 – Apr 20 |
| Peppers | Transplant outdoors | May 20 – Jun 20 |
| Eggplant | Start seeds indoors | Apr 6 – May 5 |
| Eggplant | Transplant outdoors | May 20 – Jun 20 |
| Cucumbers | Sow outdoors | May 20 – Jul 14 |
| Summer squash | Sow outdoors | May 6 – Jun 20 |
| Winter squash & pumpkins | Sow outdoors | May 20 – Jun 20 |
| Snap beans | Sow outdoors | May 6 – Aug 6 |
| Sweet corn | Sow outdoors | May 6 – Jul 4 |
| Watermelon & cantaloupe | Sow outdoors | May 20 – Jun 20 |
| Okra | Sow outdoors | May 13 – Jun 5 |
| Peas | Sow outdoors (spring) | Mar 20 – May 5 |
| Potatoes | Plant outdoors (spring) | Mar 20 – May 20 |
| Onions | Start seeds indoors (spring) | Feb 6 – Mar 5 |
| Onions | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (spring) | Mar 2 – Apr 5 |
| Broccoli | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (fall) | Jun 24 – Jul 4 |
| Broccoli | Transplant outdoors (fall) | Jul 24 – Aug 4 |
| Cabbage | Start seeds indoors (spring) | Feb 20 – Mar 20 |
| Cabbage | Transplant outdoors (spring) | Mar 20 – Apr 20 |
| Cabbage | Start seeds indoors (fall) | Jun 14 – Jul 14 |
| Cabbage | Transplant outdoors (fall) | Jul 14 – Aug 14 |
| Leaf lettuce | Sow outdoors (spring) | Mar 20 – Jun 5 |
| Leaf lettuce | Sow outdoors (fall) | Jul 14 – Aug 30 |
| Spinach | Sow outdoors (spring) | Mar 13 – Apr 26 |
| Spinach | Sow outdoors (fall) | Jul 31 – Sep 4 |
| Radishes | Sow outdoors (spring) | Mar 20 – May 10 |
| Radishes | Sow outdoors (fall) | Jul 14 – Sep 14 |
| Kale | Sow outdoors (spring) | Apr 6 – Apr 26 |
| Kale | Sow outdoors (fall) | Jul 7 – Aug 14 |
| Carrots | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Carrots | Sow outdoors (fall) | Jun 14 – Jul 30 |
| Garlic | Plant outdoors (fall) | Oct 14 – Nov 14 |
Where these dates come from
ZIP code 18055 is matched to the NOAA station Allentown Intl Ap, PA, 13 km away, at 390 ft elevation (0 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Allentown Intl Ap, PA (used) | 390 ft | Apr 20 | Oct 24 |
| Springtown 1 Nne, PA | 860 ft | Apr 21 | Oct 22 |
| Bucksville, PA | 387 ft | Apr 29 | Oct 16 |
| Phillipsburg-Easton Brg, NJ | 232 ft | Apr 18 | Oct 25 |
Frost dates near Hellertown
- Springtown, PA 18081 · last Apr 29, first Oct 16
- Bethlehem, PA 18015 · last Apr 21, first Oct 22
- Durham, PA 18039 · last Apr 29, first Oct 16
- Riegelsville, PA 18077 · last Apr 29, first Oct 16
- Center Valley, PA 18034 · last Apr 20, first Oct 24
- Coopersburg, PA 18036 · last Apr 29, first Oct 16
- Kintnersville, PA 18930 · last Apr 29, first Oct 16
- Richlandtown, PA 18955 · last Apr 29, first Oct 16
Frequently asked questions
- When is the last frost in Hellertown, PA?
- For ZIP code 18055, the average last spring frost (32°F) is April 20, based on NOAA 1991-2020 climate normals for the Allentown Intl Ap, PA weather station. There is a 1-in-10 chance of a frost after May 6.
- When is the first frost in Hellertown, PA?
- The average first fall frost (32°F) is October 24. There is a 1-in-10 chance of frost by October 8, so tender plants are at risk from that point on.
- How long is the growing season in 18055?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 184 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.