Frost dates for 17830Herndon, PA
The average last spring frost in Herndon is April 30 and the average first fall frost is October 13, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 13
- Growing season
- 166 days
Safer after May 19 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 178 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 11 · May 26 | Sep 20 · Oct 1 · Oct 15 | 143 days | 100% |
| Frost / freeze (32°F) | Apr 15 · Apr 30 · May 19 | Sep 30 · Oct 13 · Oct 31 | 166 days | 100% |
| Hard freeze (28°F) | Mar 31 · Apr 14 · May 4 | Oct 10 · Oct 26 · Nov 10 | 193 days | 100% |
Planting calendar for Herndon
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 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jun 23 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jul 3 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Jul 26 |
| Sweet corn | Sow outdoors | May 16 – Jun 23 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 13 – Jun 23 |
| Broccoli | Transplant outdoors (fall) | Jul 13 – Jul 24 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | Jun 3 – Jul 3 |
| Cabbage | Transplant outdoors (fall) | Jul 3 – Aug 3 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jul 3 – Aug 19 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Jul 20 – Aug 24 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jul 3 – Sep 3 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jun 26 – Aug 3 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | Jun 3 – Jul 19 |
| Garlic | Plant outdoors (fall) | Oct 3 – Nov 3 |
Where these dates come from
ZIP code 17830 is matched to the NOAA station Sunbury, PA, 18 km away, at 575 ft elevation (176 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sunbury, PA (used) | 575 ft | Apr 30 | Oct 13 |
| Selinsgrove 2 S, PA | 420 ft | Apr 25 | Oct 22 |
| Selinsgrove Penn Vly Ap, PA | 444 ft | Apr 27 | Oct 16 |
| Dehart Dam, PA | 537 ft | May 1 | Oct 16 |
Frost dates near Herndon
- Pillow, PA 17080 · last May 1, first Oct 16
- Dornsife, PA 17823 · last Apr 30, first Oct 13
- Dalmatia, PA 17017 · last Apr 25, first Oct 22
- Port Trevorton, PA 17864 · last Apr 25, first Oct 22
- Rebuck, PA 17867 · last Apr 30, first Oct 13
- Berrysburg, PA 17005 · last May 1, first Oct 16
- Gratz, PA 17030 · last May 1, first Oct 16
- Klingerstown, PA 17941 · last Apr 30, first Oct 13
Frequently asked questions
- When is the last frost in Herndon, PA?
- For ZIP code 17830, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Sunbury, PA weather station. There is a 1-in-10 chance of a frost after May 19.
- When is the first frost in Herndon, PA?
- The average first fall frost (32°F) is October 13. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 17830?
- 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.