Last frost date in Harrisburg, PA

Average last frost
April 15

In Harrisburg, the last spring frost comes around April 15 in an average year. Wait until May 2 if you want 90% odds of no more frost. The first fall frost usually arrives about October 23, which leaves 189 frost-free days. An early freeze before October 7 happens one year in ten.

Safe after (10% risk)
May 2
Average first frost
Oct 23
Frost-free season
189 days
Hard freeze (28°F) ends
Apr 3
Next 7 nights in Harrisburg

Frost possible in low spots Fri night, low 33°F

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2241°
  2. FriOct 2333°possible frost
  3. SatOct 2434°possible frost
  4. SunOct 2537°
  5. MonOct 2644°
  6. TueOct 2745°
  7. WedOct 2844°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 15First frost Oct 23189 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND189 frost-free days
Frost risk through the year at Harrisburg 1 NE, 0.9 miles from Harrisburg.

Planting calendar for Harrisburg

Windows count forward or back from the average frost dates above. Click a crop for dates across Pennsylvania.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesApr 22–May 6
PumpkinsApr 29–May 13
SunflowersApr 15–May 6
CucumbersApr 29–May 6
CornApr 22–May 6
Sweet potatoesMay 6–May 20
WatermelonApr 29–May 13
Green beansApr 22–May 13
ZucchiniApr 22–May 6
OkraMay 6–May 20
PeppersApr 29–May 13
BasilApr 22–May 6
Butternut squashApr 22–May 6
CantaloupeApr 29–May 13
EggplantApr 29–May 13
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 18–Apr 1
OnionsMar 4–Mar 25
CarrotsMar 25–Apr 29
LettuceApr 1–Apr 22
BroccoliMar 18–Apr 1
BeetsMar 18–Apr 29
PeasMar 4–Mar 18
CabbageMar 18–Apr 1
RadishesMar 11–Apr 22
Brussels sproutsApr 1–Apr 15
SpinachMar 4–Mar 25
CilantroApr 1–Apr 22
KaleMar 18–Apr 1
Collard greensMar 18–Apr 1
TurnipsMar 18–Apr 1
DillApr 15–Apr 29
CeleryApr 22–Apr 29
CauliflowerApr 1–Apr 15
LeeksApr 1–Apr 15
Swiss chardApr 1–Apr 29
ParsleyApr 1–Apr 22
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 9–Nov 13
GarlicOct 2–Nov 6
Daffodil bulbsSep 25–Nov 6
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 18–Apr 1
AsparagusMar 18–Apr 1

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 1Apr 15May 2Oct 7Oct 23Nov 7
Hard freeze, 28°FMar 19Apr 3Apr 16Oct 20Nov 5Nov 21

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Harrisburg 1 NE (USC00363698) sits 0.9 miles from the center of Harrisburg at 420 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Harrisburg, PA?

The average last frost date in Harrisburg is April 15, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 2.

When is the first frost in Harrisburg?

The first frost in fall usually comes around October 23. One year in ten it arrives before October 7.

How long is the growing season in Harrisburg?

About 189 days between the average last and first frost.

When should I plant tomatoes in Harrisburg?

Plant tomato seedlings outside from April 22 to May 6. Start seeds indoors six to eight weeks earlier.

Nearby in Pennsylvania

All 35 cities in Pennsylvania