When is the last frost in Harrisburg, PA?

The average (50% probability) last spring frost in Harrisburg is April 9, based on NOAA 1991–2020 normals. A 1-in-10 risk remains until April 25.

When is the first frost in Harrisburg?

The average first fall frost in Harrisburg is November 2, with a growing season of about 206 days.

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Harrisburg, Pennsylvania frost dates

Average last spring frost: April 9. Average first fall frost: November 2. That gives a growing season of about 206 days. For frost-tender plants, a safer planting date is April 25, after which a freeze happens in only 1 year in 10.

Last frost (50%)

Apr 9

1-in-10 risk after Apr 25

First frost (50%)

Nov 2

1-in-10 risk before Oct 18

Growing season

206 days

median frost-free days

Hard freeze (28°F)

Mar 30

median last 28°F in spring

Frost risk by date

Chance of frost	Spring: frost after	Fall: frost before
90%	March 28	November 15
70%	April 4	November 7
50%	April 9	November 2
30%	April 15	October 27
10%	April 25	October 18

Read the spring column like this: there is a 10% chance of a 32°F freeze after April 25. These are NOAA probabilities for the Middletown Harrisburg International Airport weather station (USW00014711, elevation 95 m), 1991–2020.

Harrisburg vegetable planting calendar

Dates count from the 50% last-frost date (April 9). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (Apr 25) is the cautious choice.

Crop	Start seeds indoors	Plant out
Beans	Mar 19	Apr 16 (usually sown directly in the garden)
Broccoli	Jan 29	Mar 12
Brussels sprouts	Jan 29	Mar 12
Cabbage	Jan 22	Mar 5
Cauliflower	Feb 12	Mar 26
Sweet corn	Mar 12	Apr 9 (usually sown directly in the garden)
Cucumbers	Mar 26	Apr 16
Kale	Jan 22	Mar 5
Leeks	Dec 25	Mar 5
Lettuce	Feb 19	Mar 26
Melons	Apr 2	Apr 23
Onions	Dec 18	Feb 26 (from seed; sets and transplants go out at the same time)
Peas	Feb 12	Mar 12 (usually sown directly in the garden)
Peppers	Feb 26	Apr 23
Squash	Apr 2	Apr 23
Tomatoes	Feb 12	Apr 9

Offsets from Oregon State University Extension's seed-starting table. "Plant out" means transplant, or sow directly for crops usually grown from seed.

Fall frost and season extension

The first fall freeze usually arrives around November 2. There's a 1-in-10 chance it comes before October 18. Harvest tender crops such as basil, tomatoes, peppers and squash before then, or cover them on cold nights. Cool-season crops like kale, cabbage and Brussels sprouts handle light frost, and often taste sweeter after it. A hard freeze (28°F) typically comes around November 14.

Nearby cities

City	Last frost (50%)	First frost (50%)	Distance
Baltimore, MD	Apr 10	Oct 31	~114 km
Allentown, PA	Apr 20	Oct 24	~122 km
Philadelphia, PA	Apr 2	Nov 10	~135 km
Washington, DC	Mar 24	Nov 18	~151 km
Newark, NJ	Apr 2	Nov 10	~227 km
New York, NY	Apr 2	Nov 14	~259 km

More: all Pennsylvania frost dates