Frost Dates: First and last frost dates for Effingham, IL

ℹ️ How to read these charts for the spring

As spring unfolds, the risk of frost gradually decreases each day until your tender plants are finally safe. The probabilities shown in the chart help you make smart decisions about when to plant.

While frost typically forms at 32°F, tender plants can be damaged even when temperatures are slightly higher. Air temperatures are often measured several feet above the ground, but temperatures at plant level can be several degrees colder. Protected areas like porches help by blocking radiational cooling. Given these variables, we consider 36°F the "caution zone" for frost-sensitive plants.

Key dates for your spring planting:

  • By May 14, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around April 29, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before April 19, there's still an 80% risk of frost — too early for tomatoes and other tender plants unless you're prepared to protect them

If the 10-day forecast shows no temperatures below 40°F, you might safely plant earlier than the above dates suggest. Many gardeners watch for this weather window to get a head start on the growing season.

In the Spring
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
Last 16° Mar 18 Mar 11 Mar 7 Mar 2 Feb 27 Feb 23 Feb 19 Feb 14 Feb 7
Last 20° Mar 25 Mar 21 Mar 18 Mar 16 Mar 14 Mar 12 Mar 10 Mar 7 Mar 4
Last 24° Apr 10 Apr 5 Apr 1 Mar 29 Mar 26 Mar 23 Mar 19 Mar 15 Mar 10
Last 28° Apr 16 Apr 12 Apr 9 Apr 7 Apr 4 Apr 2 Mar 30 Mar 27 Mar 23
Last 32° May 3 Apr 27 Apr 23 Apr 19 Apr 16 Apr 12 Apr 9 Apr 4 Mar 30
Last 36° May 14 May 9 May 5 May 2 Apr 29 Apr 26 Apr 23 Apr 19 Apr 14

ℹ️ How to read these charts for the fall

As summer ends in Effingham, IL, nighttime temperatures begin to drop, and your risk of frost increases with each passing day. Knowing when to expect frost helps you harvest sensitive crops and extend your growing season with protection methods.

The chart below shows the probability of experiencing specific temperatures on various dates. Here's what this means for your garden:

1
Early warning: Around October 7, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By October 17, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By October 26, there's an 80% chance of seeing 32°F — most tender plants will be damaged without protection
4
Another perspective: You have only a 1 in 5 chance of making it past October 26 without a freezing night

These probabilities help you time your end-of-season harvests and know when to apply protective measures like row covers, cloches, or cold frames to extend your harvest.

In the Fall
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
First 16° Nov 15 Nov 21 Nov 26 Nov 30 Dec 4 Dec 7 Dec 11 Dec 16 Dec 22
First 20° Nov 2 Nov 8 Nov 13 Nov 17 Nov 21 Nov 24 Nov 28 Dec 3 Dec 9
First 24° Oct 26 Nov 2 Nov 6 Nov 10 Nov 13 Nov 17 Nov 21 Nov 25 Dec 1
First 28° Oct 12 Oct 18 Oct 22 Oct 26 Oct 29 Nov 1 Nov 5 Nov 9 Nov 14
First 32° Oct 3 Oct 7 Oct 11 Oct 14 Oct 17 Oct 19 Oct 22 Oct 26 Oct 31
First 36° Sep 24 Sep 28 Oct 1 Oct 3 Oct 6 Oct 8 Oct 11 Oct 14 Oct 18

📍 Frost Dates for other nearby locations

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Data is provided by the NOAA National Centers for Environmental Information.