Last frost date in Grayslake, IL

Average last frost
April 29

In Grayslake, the last spring frost comes around April 29 in an average year. Wait until May 15 if you want 90% odds of no more frost. The first fall frost usually arrives about October 20, which leaves 172 frost-free days. An early freeze before October 4 happens one year in ten.

Safe after (10% risk)
May 15
Average first frost
Oct 20
Frost-free season
172 days
Hard freeze (28°F) ends
Apr 16
Next 7 nights in Grayslake

No frost in the next 7 nights

Later than usual: the average first frost here is October 20.

National Weather Service forecast, updated Oct 22, 12:24 UTC

  1. ThuOct 2246°
  2. FriOct 2348°
  3. SatOct 2451°
  4. SunOct 2551°
  5. MonOct 2648°
  6. TueOct 2744°
  7. WedOct 2846°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 29First frost Oct 20172 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND172 frost-free days
Frost risk through the year at Mundelein 4 WSW, 6.3 miles from Grayslake.

Planting calendar for Grayslake

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 6–May 20
PumpkinsMay 13–May 27
SunflowersApr 29–May 20
CucumbersMay 13–May 20
CornMay 6–May 20
Sweet potatoesMay 20–Jun 3
WatermelonMay 13–May 27
Green beansMay 6–May 27
ZucchiniMay 6–May 20
OkraMay 20–Jun 3
PeppersMay 13–May 27
BasilMay 6–May 20
Butternut squashMay 6–May 20
CantaloupeMay 13–May 27
EggplantMay 13–May 27
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 1–Apr 15
OnionsMar 18–Apr 8
CarrotsApr 8–May 13
LettuceApr 15–May 6
BroccoliApr 1–Apr 15
BeetsApr 1–May 13
PeasMar 18–Apr 1
CabbageApr 1–Apr 15
RadishesMar 25–May 6
Brussels sproutsApr 15–Apr 29
SpinachMar 18–Apr 8
CilantroApr 15–May 6
KaleApr 1–Apr 15
Collard greensApr 1–Apr 15
TurnipsApr 1–Apr 15
DillApr 29–May 13
CeleryMay 6–May 13
CauliflowerApr 15–Apr 29
LeeksApr 15–Apr 29
Swiss chardApr 15–May 13
ParsleyApr 15–May 6
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 6–Nov 10
GarlicSep 29–Nov 3
Daffodil bulbsSep 22–Nov 3
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 1–Apr 15
AsparagusApr 1–Apr 15

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 14Apr 29May 15Oct 4Oct 20Nov 1
Hard freeze, 28°FApr 2Apr 16May 4Oct 16Oct 31Nov 12

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 Mundelein 4 WSW (USC00115961) sits 6.3 miles from the center of Grayslake at 840 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 Grayslake, IL?

The average last frost date in Grayslake is April 29, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 15.

When is the first frost in Grayslake?

The first frost in fall usually comes around October 20. One year in ten it arrives before October 4.

How long is the growing season in Grayslake?

About 172 days between the average last and first frost.

When should I plant tomatoes in Grayslake?

Plant tomato seedlings outside from May 6 to May 20. Start seeds indoors six to eight weeks earlier.

Nearby in Illinois

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