Last frost date in Waltham, MA
In Waltham, the last spring frost comes around April 28 in an average year. Wait until May 12 if you want 90% odds of no more frost. The first fall frost usually arrives about October 10, which leaves 165 frost-free days. An early freeze before September 28 happens one year in ten.
- Safe after (10% risk)
- May 12
- Average first frost
- Oct 10
- Frost-free season
- 165 days
- Hard freeze (28°F) ends
- Apr 12
Frost likely Fri night, low 31°F
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2237°
- FriOct 2331°frost
- SatOct 2432°frost
- SunOct 2537°
- MonOct 2643°
- TueOct 2739°
- WedOct 2840°
Planting calendar for Waltham
Windows count forward or back from the average frost dates above. Click a crop for dates across Massachusetts.
TomatoesMay 5–May 19
PumpkinsMay 12–May 26
SunflowersApr 28–May 19
CucumbersMay 12–May 19
CornMay 5–May 19
Sweet potatoesMay 19–Jun 2
WatermelonMay 12–May 26
Green beansMay 5–May 26
ZucchiniMay 5–May 19
OkraMay 19–Jun 2
PeppersMay 12–May 26
BasilMay 5–May 19
Butternut squashMay 5–May 19
CantaloupeMay 12–May 26
EggplantMay 12–May 26
PotatoesMar 31–Apr 14
OnionsMar 17–Apr 7
CarrotsApr 7–May 12
LettuceApr 14–May 5
BroccoliMar 31–Apr 14
BeetsMar 31–May 12
PeasMar 17–Mar 31
CabbageMar 31–Apr 14
RadishesMar 24–May 5
Brussels sproutsApr 14–Apr 28
SpinachMar 17–Apr 7
CilantroApr 14–May 5
KaleMar 31–Apr 14
Collard greensMar 31–Apr 14
TurnipsMar 31–Apr 14
DillApr 28–May 12
CeleryMay 5–May 12
CauliflowerApr 14–Apr 28
LeeksApr 14–Apr 28
Swiss chardApr 14–May 12
ParsleyApr 14–May 5
Tulip bulbsSep 26–Oct 31
GarlicSep 19–Oct 24
Daffodil bulbsSep 12–Oct 24
StrawberriesMar 31–Apr 14
AsparagusMar 31–Apr 14Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Apr 13 | Apr 28 | May 12 | Sep 28 | Oct 10 | Oct 28 |
| Hard freeze, 28°F | Apr 1 | Apr 12 | Apr 29 | Oct 7 | Oct 25 | Nov 8 |
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 Bedford Hanscom Field (USW00014702) sits 6.1 miles from the center of Waltham at 133 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 Waltham, MA?
The average last frost date in Waltham is April 28, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 12.
When is the first frost in Waltham?
The first frost in fall usually comes around October 10. One year in ten it arrives before September 28.
How long is the growing season in Waltham?
About 165 days between the average last and first frost.
When should I plant tomatoes in Waltham?
Plant tomato seedlings outside from May 5 to May 19. Start seeds indoors six to eight weeks earlier.