Last frost date in Northbrook, IL

Average last frost
April 26

In Northbrook, the last spring frost comes around April 26 in an average year. Wait until May 11 if you want 90% odds of no more frost. The first fall frost usually arrives about October 21, which leaves 176 frost-free days. An early freeze before October 5 happens one year in ten.

Safe after (10% risk)
May 11
Average first frost
Oct 21
Frost-free season
176 days
Hard freeze (28°F) ends
Apr 13
Next 7 nights in Northbrook

No frost in the next 7 nights

Later than usual: the average first frost here is October 21.

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

  1. ThuOct 2249°
  2. FriOct 2350°
  3. SatOct 2452°
  4. SunOct 2552°
  5. MonOct 2649°
  6. TueOct 2746°
  7. WedOct 2847°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 26First frost Oct 21176 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND176 frost-free days
Frost risk through the year at Chicago Botanic Garden, 2.7 miles from Northbrook.

Planting calendar for Northbrook

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 3–May 17
PumpkinsMay 10–May 24
SunflowersApr 26–May 17
CucumbersMay 10–May 17
CornMay 3–May 17
Sweet potatoesMay 17–May 31
WatermelonMay 10–May 24
Green beansMay 3–May 24
ZucchiniMay 3–May 17
OkraMay 17–May 31
PeppersMay 10–May 24
BasilMay 3–May 17
Butternut squashMay 3–May 17
CantaloupeMay 10–May 24
EggplantMay 10–May 24
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 29–Apr 12
OnionsMar 15–Apr 5
CarrotsApr 5–May 10
LettuceApr 12–May 3
BroccoliMar 29–Apr 12
BeetsMar 29–May 10
PeasMar 15–Mar 29
CabbageMar 29–Apr 12
RadishesMar 22–May 3
Brussels sproutsApr 12–Apr 26
SpinachMar 15–Apr 5
CilantroApr 12–May 3
KaleMar 29–Apr 12
Collard greensMar 29–Apr 12
TurnipsMar 29–Apr 12
DillApr 26–May 10
CeleryMay 3–May 10
CauliflowerApr 12–Apr 26
LeeksApr 12–Apr 26
Swiss chardApr 12–May 10
ParsleyApr 12–May 3
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 7–Nov 11
GarlicSep 30–Nov 4
Daffodil bulbsSep 23–Nov 4
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 29–Apr 12
AsparagusMar 29–Apr 12

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 11Apr 26May 11Oct 5Oct 21Nov 2
Hard freeze, 28°FMar 31Apr 13Apr 28Oct 17Nov 1Nov 14

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 Chicago Botanic Garden (USC00111497) sits 2.7 miles from the center of Northbrook at 630 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 Northbrook, IL?

The average last frost date in Northbrook is April 26, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 11.

When is the first frost in Northbrook?

The first frost in fall usually comes around October 21. One year in ten it arrives before October 5.

How long is the growing season in Northbrook?

About 176 days between the average last and first frost.

When should I plant tomatoes in Northbrook?

Plant tomato seedlings outside from May 3 to May 17. Start seeds indoors six to eight weeks earlier.

Nearby in Illinois

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