Frost Dates: First and last frost dates for Hill City, SD

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 July 18, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 23, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 6, 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° May 4 Apr 30 Apr 27 Apr 24 Apr 21 Apr 19 Apr 16 Apr 13 Apr 8
Last 20° May 18 May 13 May 9 May 5 May 2 Apr 29 Apr 25 Apr 21 Apr 16
Last 24° May 24 May 20 May 17 May 15 May 13 May 10 May 8 May 5 May 1
Last 28° Jun 10 Jun 5 Jun 2 May 30 May 27 May 24 May 21 May 17 May 12
Last 32° Jul 5 Jun 26 Jun 19 Jun 14 Jun 9 Jun 3 May 29 May 22 May 13
Last 36° Jul 18 Jul 9 Jul 3 Jun 28 Jun 23 Jun 18 Jun 13 Jun 6 May 29

ℹ️ How to read these charts for the fall

As summer ends in Hill City, SD, 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 August 7, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By August 24, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 10, 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 10 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° Sep 23 Sep 29 Oct 4 Oct 8 Oct 11 Oct 15 Oct 19 Oct 23 Oct 30
First 20° Aug 28 Sep 7 Sep 14 Sep 20 Sep 26 Oct 1 Oct 7 Oct 14 Oct 24
First 24° Aug 19 Aug 28 Sep 4 Sep 10 Sep 16 Sep 21 Sep 27 Oct 4 Oct 14
First 28° Aug 4 Aug 14 Aug 22 Aug 28 Sep 2 Sep 8 Sep 14 Sep 22 Oct 2
First 32° Jul 31 Aug 7 Aug 14 Aug 19 Aug 24 Aug 29 Sep 3 Sep 10 Sep 18
First 36° Jul 29 Aug 4 Aug 9 Aug 14 Aug 18 Aug 22 Aug 27 Sep 1 Sep 9

📍 Frost Dates for other nearby locations

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