Last frost date in Marshalltown, IA
The average last frost in Marshalltown is April 28. By May 11 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 7, which leaves 162 frost-free days. An early freeze before September 22 happens one year in ten.
- Safe after (10% risk)
- May 11
- Average first frost
- Oct 7
- Frost-free season
- 162 days
- Hard freeze (28°F) ends
- Apr 17
No frost in the next 7 nights
Later than usual: the average first frost here is October 7.
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2253°
- FriOct 2356°
- SatOct 2454°
- SunOct 2550°
- MonOct 2645°
- TueOct 2743°
- WedOct 2844°
Planting calendar for Marshalltown
Windows count forward or back from the average frost dates above. Click a crop for dates across Iowa.
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 23–Oct 28
GarlicSep 16–Oct 21
Daffodil bulbsSep 9–Oct 21
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 11 | Sep 22 | Oct 7 | Oct 21 |
| Hard freeze, 28°F | Apr 3 | Apr 17 | May 2 | Oct 1 | Oct 18 | Oct 31 |
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 Marshalltown (USC00135198) sits 2.3 miles from the center of Marshalltown at 870 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 Marshalltown, IA?
The average last frost date in Marshalltown is April 28, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 11.
When is the first frost in Marshalltown?
The first frost in fall usually comes around October 7. One year in ten it arrives before September 22.
How long is the growing season in Marshalltown?
About 162 days between the average last and first frost.
When should I plant tomatoes in Marshalltown?
Plant tomato seedlings outside from May 5 to May 19. Start seeds indoors six to eight weeks earlier.
Nearby in Iowa
- AmesApr 26
- AltoonaApr 23
- Cedar FallsApr 27
- AnkenyApr 23
- WaterlooApr 27
- JohnstonApr 19
- Des MoinesApr 18
- UrbandaleApr 19
- West Des MoinesApr 18
- WaukeeApr 18
- Cedar RapidsApr 27
- MarionApr 28