Frost Dates for Harrisburg, PA
In Harrisburg, PA, the average last spring frost is around Apr 15 and the average first fall frost around Oct 23, for a growing season of about 189 days. For frost-tender plants, wait until May 2, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Harrisburg 1 Ne, PA weather station, under 1 mile away, elevation 420 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | May 2 | Oct 7 |
| 20% | Apr 26 | Oct 13 |
| 30% | Apr 21 | Oct 16 |
| 40% | Apr 17 | Oct 20 |
| 50% | Apr 15 | Oct 23 |
| 60% | Apr 12 | Oct 26 |
| 70% | Apr 9 | Oct 30 |
| 80% | Apr 6 | Nov 2 |
| 90% | Apr 1 | Nov 7 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | Apr 30 | Oct 12 |
| Frost / freeze (32°F) | Apr 15 | Oct 23 |
| Hard freeze (28°F) | Apr 3 | Nov 5 |
Planting calendar for Harrisburg
Transplant Apr 22 – May 6
Transplant Apr 29 – May 13
Transplant Apr 29 – May 13
Transplant Apr 22 – May 6
Sow or transplant Apr 22 – May 6
Sow or transplant Apr 22 – May 6
Sow or transplant Apr 29 – May 13
Sow or transplant Mar 18 – Apr 1
Fall sowing Aug 28 – Sep 25
Fall sowing Aug 28 – Sep 18
Fall sowing Aug 14 – Aug 28
Sow or transplant Mar 18 – Apr 1
Fall sowing Aug 14 – Sep 11
Transplant Apr 1 – Apr 15
Fall sowing Jul 31 – Aug 14
Transplant Mar 25 – Apr 8
Fall sowing Jul 31 – Aug 14
Fall sowing Jul 31 – Aug 14
Fall sowing Sep 11 – Oct 2
Fall sowing Aug 14 – Aug 28
Plant Mar 18 – Apr 1
Based on the average last frost (Apr 15) and first frost (Oct 23). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.