Last frost date in Algonquin, IL

Average last frost
April 26

Expect the last frost in Algonquin around April 26. Frost after May 12 happens in only one year out of ten. The first fall frost usually arrives about October 18, which leaves 174 frost-free days. An early freeze before October 3 happens one year in ten.

Safe after (10% risk)
May 12
Average first frost
Oct 18
Frost-free season
174 days
Hard freeze (28°F) ends
Apr 14
Next 7 nights in Algonquin

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 2247°
  2. FriOct 2347°
  3. SatOct 2450°
  4. SunOct 2550°
  5. MonOct 2647°
  6. TueOct 2744°
  7. WedOct 2845°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 26First frost Oct 18174 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND174 frost-free days
Frost risk through the year at Elgin, 6.9 miles from Algonquin.

Planting calendar for Algonquin

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 4–Nov 8
GarlicSep 27–Nov 1
Daffodil bulbsSep 20–Nov 1
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 12Apr 26May 12Oct 3Oct 18Oct 31
Hard freeze, 28°FApr 1Apr 14Apr 29Oct 15Oct 29Nov 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 Elgin (USC00112736) sits 6.9 miles from the center of Algonquin at 763 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 Algonquin, IL?

The average last frost date in Algonquin is April 26, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 12.

When is the first frost in Algonquin?

The first frost in fall usually comes around October 18. One year in ten it arrives before October 3.

How long is the growing season in Algonquin?

About 174 days between the average last and first frost.

When should I plant tomatoes in Algonquin?

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

Nearby in Illinois

All 121 cities in Illinois