Frost Dates: First and last frost dates for Big Falls, MN

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 June 30, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 12, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before May 31, 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° Apr 21 Apr 17 Apr 14 Apr 12 Apr 9 Apr 7 Apr 5 Apr 2 Mar 29
Last 20° May 5 Apr 29 Apr 25 Apr 22 Apr 19 Apr 16 Apr 13 Apr 9 Apr 3
Last 24° May 11 May 8 May 5 May 3 May 1 Apr 29 Apr 26 Apr 24 Apr 20
Last 28° May 26 May 21 May 17 May 14 May 11 May 8 May 5 May 1 Apr 26
Last 32° Jun 14 Jun 8 Jun 4 May 31 May 28 May 25 May 21 May 17 May 12
Last 36° Jun 30 Jun 24 Jun 19 Jun 15 Jun 12 Jun 8 Jun 4 May 31 May 24

ℹ️ How to read these charts for the fall

As summer ends in Big Falls, MN, 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 September 3, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 12, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 20, 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 September 20 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° Oct 14 Oct 19 Oct 23 Oct 27 Oct 30 Nov 2 Nov 6 Nov 10 Nov 16
First 20° Oct 3 Oct 9 Oct 13 Oct 16 Oct 19 Oct 22 Oct 26 Oct 30 Nov 4
First 24° Sep 21 Sep 27 Sep 30 Oct 4 Oct 7 Oct 10 Oct 13 Oct 16 Oct 22
First 28° Sep 15 Sep 19 Sep 21 Sep 24 Sep 26 Sep 28 Oct 1 Oct 3 Oct 7
First 32° Aug 29 Sep 3 Sep 6 Sep 9 Sep 12 Sep 14 Sep 17 Sep 20 Sep 25
First 36° Aug 16 Aug 21 Aug 25 Aug 28 Aug 31 Sep 3 Sep 7 Sep 11 Sep 16

📍 Frost Dates for other nearby locations

Or enter a new zipcode:

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