Last frost date in Rock Island, IL

Average last frost
April 24

The average last frost in Rock Island is April 24. By May 9 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 18, which leaves 176 frost-free days. An early freeze before October 4 happens one year in ten.

Safe after (10% risk)
May 9
Average first frost
Oct 18
Frost-free season
176 days
Hard freeze (28°F) ends
Apr 12
Next 7 nights in Rock Island

No frost in the next 7 nights

Later than usual: the average first frost here is October 18.

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

  1. ThuOct 2253°
  2. FriOct 2354°
  3. SatOct 2454°
  4. SunOct 2554°
  5. MonOct 2650°
  6. TueOct 2747°
  7. WedOct 2849°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 24First frost Oct 18176 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND176 frost-free days
Frost risk through the year at Moline Quad City International Airport, 3.2 miles from Rock Island.

Planting calendar for Rock Island

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

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 1–May 15
PumpkinsMay 8–May 22
SunflowersApr 24–May 15
CucumbersMay 8–May 15
CornMay 1–May 15
Sweet potatoesMay 15–May 29
WatermelonMay 8–May 22
Green beansMay 1–May 22
ZucchiniMay 1–May 15
OkraMay 15–May 29
PeppersMay 8–May 22
BasilMay 1–May 15
Butternut squashMay 1–May 15
CantaloupeMay 8–May 22
EggplantMay 8–May 22
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 27–Apr 10
OnionsMar 13–Apr 3
CarrotsApr 3–May 8
LettuceApr 10–May 1
BroccoliMar 27–Apr 10
BeetsMar 27–May 8
PeasMar 13–Mar 27
CabbageMar 27–Apr 10
RadishesMar 20–May 1
Brussels sproutsApr 10–Apr 24
SpinachMar 13–Apr 3
CilantroApr 10–May 1
KaleMar 27–Apr 10
Collard greensMar 27–Apr 10
TurnipsMar 27–Apr 10
DillApr 24–May 8
CeleryMay 1–May 8
CauliflowerApr 10–Apr 24
LeeksApr 10–Apr 24
Swiss chardApr 10–May 8
ParsleyApr 10–May 1
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 4–Nov 8
GarlicSep 27–Nov 1
Daffodil bulbsSep 20–Nov 1
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 27–Apr 10
AsparagusMar 27–Apr 10

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 9Apr 24May 9Oct 4Oct 18Oct 28
Hard freeze, 28°FMar 30Apr 12Apr 30Oct 15Oct 27Nov 7

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 Moline Quad City International Airport (USW00014923) sits 3.2 miles from the center of Rock Island at 592 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 Rock Island, IL?

The average last frost date in Rock Island is April 24, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 9.

When is the first frost in Rock Island?

The first frost in fall usually comes around October 18. One year in ten it arrives before October 4.

How long is the growing season in Rock Island?

About 176 days between the average last and first frost.

When should I plant tomatoes in Rock Island?

Plant tomato seedlings outside from May 1 to May 15. Start seeds indoors six to eight weeks earlier.

Nearby in Illinois

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