Last frost date in Naperville, IL
The average last frost in Naperville is April 28. By May 14 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 16, which leaves 169 frost-free days. An early freeze before October 1 happens one year in ten.
- Safe after (10% risk)
- May 14
- Average first frost
- Oct 16
- Frost-free season
- 169 days
- Hard freeze (28°F) ends
- Apr 16
No frost in the next 7 nights
Later than usual: the average first frost here is October 16.
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2247°
- FriOct 2348°
- SatOct 2450°
- SunOct 2551°
- MonOct 2649°
- TueOct 2746°
- WedOct 2846°
Planting calendar for Naperville
Windows count forward or back from the average frost dates above. Click a crop for dates across Illinois.
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 bulbsOct 2–Nov 6
GarlicSep 25–Oct 30
Daffodil bulbsSep 18–Oct 30
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 14 | Apr 28 | May 14 | Oct 1 | Oct 16 | Oct 29 |
| Hard freeze, 28°F | Apr 2 | Apr 16 | May 4 | Oct 12 | Oct 26 | 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 Lisle-morton Arboretum (USC00115097) sits 6.4 miles from the center of Naperville at 680 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 Naperville, IL?
The average last frost date in Naperville is April 28, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 14.
When is the first frost in Naperville?
The first frost in fall usually comes around October 16. One year in ten it arrives before October 1.
How long is the growing season in Naperville?
About 169 days between the average last and first frost.
When should I plant tomatoes in Naperville?
Plant tomato seedlings outside from May 5 to May 19. Start seeds indoors six to eight weeks earlier.
Nearby in Illinois
- LisleApr 28
- BolingbrookApr 20
- WoodridgeApr 28
- AuroraApr 19
- Downers GroveApr 28
- WheatonApr 28
- RomeovilleApr 20
- DarienApr 19
- PlainfieldApr 20
- Glen EllynApr 28
- OswegoApr 19
- WestmontApr 28