Last frost date in Bethlehem, PA
In Bethlehem, the last spring frost comes around April 20 in an average year. Wait until May 6 if you want 90% odds of no more frost. The first fall frost usually arrives about October 24, which leaves 184 frost-free days. An early freeze before October 8 happens one year in ten.
- Safe after (10% risk)
- May 6
- Average first frost
- Oct 24
- Frost-free season
- 184 days
- Hard freeze (28°F) ends
- Apr 5
Frost likely Fri night, low 32°F
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2239°
- FriOct 2332°frost
- SatOct 2433°possible frost
- SunOct 2537°
- MonOct 2643°
- TueOct 2742°
- WedOct 2843°
Planting calendar for Bethlehem
Windows count forward or back from the average frost dates above. Click a crop for dates across Pennsylvania.
TomatoesApr 27–May 11
PumpkinsMay 4–May 18
SunflowersApr 20–May 11
CucumbersMay 4–May 11
CornApr 27–May 11
Sweet potatoesMay 11–May 25
WatermelonMay 4–May 18
Green beansApr 27–May 18
ZucchiniApr 27–May 11
OkraMay 11–May 25
PeppersMay 4–May 18
BasilApr 27–May 11
Butternut squashApr 27–May 11
CantaloupeMay 4–May 18
EggplantMay 4–May 18
PotatoesMar 23–Apr 6
OnionsMar 9–Mar 30
CarrotsMar 30–May 4
LettuceApr 6–Apr 27
BroccoliMar 23–Apr 6
BeetsMar 23–May 4
PeasMar 9–Mar 23
CabbageMar 23–Apr 6
RadishesMar 16–Apr 27
Brussels sproutsApr 6–Apr 20
SpinachMar 9–Mar 30
CilantroApr 6–Apr 27
KaleMar 23–Apr 6
Collard greensMar 23–Apr 6
TurnipsMar 23–Apr 6
DillApr 20–May 4
CeleryApr 27–May 4
CauliflowerApr 6–Apr 20
LeeksApr 6–Apr 20
Swiss chardApr 6–May 4
ParsleyApr 6–Apr 27
Tulip bulbsOct 10–Nov 14
GarlicOct 3–Nov 7
Daffodil bulbsSep 26–Nov 7
StrawberriesMar 23–Apr 6
AsparagusMar 23–Apr 6Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Apr 6 | Apr 20 | May 6 | Oct 8 | Oct 24 | Nov 6 |
| Hard freeze, 28°F | Mar 23 | Apr 5 | Apr 18 | Oct 19 | Nov 4 | Nov 18 |
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 Allentown International Airport (USW00014737) sits 4.6 miles from the center of Bethlehem at 390 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 Bethlehem, PA?
The average last frost date in Bethlehem is April 20, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 6.
When is the first frost in Bethlehem?
The first frost in fall usually comes around October 24. One year in ten it arrives before October 8.
How long is the growing season in Bethlehem?
About 184 days between the average last and first frost.
When should I plant tomatoes in Bethlehem?
Plant tomato seedlings outside from April 27 to May 11. Start seeds indoors six to eight weeks earlier.
Nearby in Pennsylvania
- AllentownApr 20
- EastonApr 18
- PottstownApr 20
- NorristownApr 8
- PhoenixvilleApr 18
- ReadingApr 14
- King of PrussiaApr 8
- HazletonApr 30
- LevittownApr 21
- PhiladelphiaMar 30
- Drexel HillApr 2
- Wilkes-BarreApr 23