Frost dates for 18195Allentown, PA
The average last spring frost in Allentown is April 26 and the average first fall frost is October 14, giving a typical growing season of about 171 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 26
- Average first fall frost
- Oct 14
- Growing season
- 171 days
Safer after May 13 (1-in-10 risk)
Possible by Oct 1 (1-in-10 risk)
Last frost typically in 174 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 22 · May 8 · May 24 | Sep 24 · Oct 5 · Oct 18 | 151 days | 100% |
| Frost / freeze (32°F) | Apr 10 · Apr 26 · May 13 | Oct 1 · Oct 14 · Oct 31 | 171 days | 100% |
| Hard freeze (28°F) | Mar 29 · Apr 10 · Apr 29 | Oct 10 · Oct 26 · Nov 12 | 198 days | 100% |
Planting calendar for Allentown
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 26 – Jun 1 |
| Tomatoes | Transplant outdoors | May 12 – Jun 24 |
| Peppers | Start seeds indoors | Mar 26 – Apr 26 |
| Peppers | Transplant outdoors | May 26 – Jun 26 |
| Eggplant | Start seeds indoors | Apr 12 – May 11 |
| Eggplant | Transplant outdoors | May 26 – Jun 26 |
| Cucumbers | Sow outdoors | May 26 – Jul 4 |
| Summer squash | Sow outdoors | May 12 – Jun 26 |
| Winter squash & pumpkins | Sow outdoors | May 26 – Jun 26 |
| Snap beans | Sow outdoors | May 12 – Jul 27 |
| Sweet corn | Sow outdoors | May 12 – Jun 24 |
| Watermelon & cantaloupe | Sow outdoors | May 26 – Jun 26 |
| Okra | Sow outdoors | May 19 – Jun 11 |
| Peas | Sow outdoors (spring) | Mar 26 – May 11 |
| Potatoes | Plant outdoors (spring) | Mar 26 – May 26 |
| Onions | Start seeds indoors (spring) | Feb 12 – Mar 11 |
| Onions | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (spring) | Mar 8 – Apr 11 |
| Broccoli | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (fall) | Jun 14 – Jun 24 |
| Broccoli | Transplant outdoors (fall) | Jul 14 – Jul 25 |
| Cabbage | Start seeds indoors (spring) | Feb 26 – Mar 26 |
| Cabbage | Transplant outdoors (spring) | Mar 26 – Apr 26 |
| Cabbage | Start seeds indoors (fall) | Jun 4 – Jul 4 |
| Cabbage | Transplant outdoors (fall) | Jul 4 – Aug 4 |
| Leaf lettuce | Sow outdoors (spring) | Mar 26 – Jun 11 |
| Leaf lettuce | Sow outdoors (fall) | Jul 4 – Aug 20 |
| Spinach | Sow outdoors (spring) | Mar 19 – May 2 |
| Spinach | Sow outdoors (fall) | Jul 21 – Aug 25 |
| Radishes | Sow outdoors (spring) | Mar 26 – May 16 |
| Radishes | Sow outdoors (fall) | Jul 4 – Sep 4 |
| Kale | Sow outdoors (spring) | Apr 12 – May 2 |
| Kale | Sow outdoors (fall) | Jun 27 – Aug 4 |
| Carrots | Sow outdoors (spring) | Apr 26 – Jun 11 |
| Carrots | Sow outdoors (fall) | Jun 4 – Jul 20 |
| Garlic | Plant outdoors (fall) | Oct 4 – Nov 4 |
Where these dates come from
ZIP code 18195 is matched to the NOAA station Rodale Rsch Ctr, PA, 9 km away, at 550 ft elevation (84 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Rodale Rsch Ctr, PA (used) | 550 ft | Apr 26 | Oct 14 |
| Allentown Intl Ap, PA | 390 ft | Apr 20 | Oct 24 |
| Lehighton 1Ssw, PA | 455 ft | Apr 21 | Oct 23 |
| Springtown 1 Nne, PA | 860 ft | Apr 21 | Oct 22 |
Frost dates near Allentown
- Allentown, PA 18106 · last Apr 26, first Oct 14
- Fogelsville, PA 18051 · last Apr 26, first Oct 14
- Breinigsville, PA 18031 · last Apr 26, first Oct 14
- Trexlertown, PA 18087 · last Apr 26, first Oct 14
- Orefield, PA 18069 · last Apr 20, first Oct 24
- East Texas, PA 18046 · last Apr 20, first Oct 24
- Maxatawny, PA 19538 · last Apr 26, first Oct 14
- Macungie, PA 18062 · last Apr 26, first Oct 14
Frequently asked questions
- When is the last frost in Allentown, PA?
- For ZIP code 18195, the average last spring frost (32°F) is April 26, based on NOAA 1991-2020 climate normals for the Rodale Rsch Ctr, PA weather station. There is a 1-in-10 chance of a frost after May 13.
- When is the first frost in Allentown, PA?
- The average first fall frost (32°F) is October 14. There is a 1-in-10 chance of frost by October 1, so tender plants are at risk from that point on.
- How long is the growing season in 18195?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 171 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.