Frost Dates: First and last frost dates for Enterprise, OR

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 31, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around July 17, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before July 8, 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 17 Apr 7 Mar 31 Mar 25 Mar 19 Mar 14 Mar 7 Feb 28 Feb 18
Last 20° May 2 Apr 25 Apr 20 Apr 16 Apr 12 Apr 8 Apr 3 Mar 29 Mar 22
Last 24° May 31 May 23 May 17 May 12 May 7 May 2 Apr 27 Apr 21 Apr 12
Last 28° Jun 28 Jun 18 Jun 11 Jun 5 May 30 May 24 May 18 May 11 May 1
Last 32° Jul 17 Jul 11 Jul 6 Jul 2 Jun 29 Jun 25 Jun 21 Jun 17 Jun 11
Last 36° Jul 31 Jul 26 Jul 23 Jul 20 Jul 17 Jul 14 Jul 11 Jul 8 Jul 3

ℹ️ How to read these charts for the fall

As summer ends in Enterprise, OR, 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 16, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By August 28, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 8, 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 8 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 6 Oct 13 Oct 18 Oct 22 Oct 26 Oct 30 Nov 3 Nov 8 Nov 15
First 20° Sep 24 Sep 30 Oct 4 Oct 7 Oct 11 Oct 14 Oct 18 Oct 22 Oct 27
First 24° Sep 11 Sep 16 Sep 20 Sep 23 Sep 26 Sep 29 Oct 2 Oct 6 Oct 11
First 28° Sep 1 Sep 4 Sep 7 Sep 10 Sep 12 Sep 14 Sep 16 Sep 19 Sep 23
First 32° Aug 11 Aug 16 Aug 21 Aug 24 Aug 28 Aug 31 Sep 4 Sep 8 Sep 14
First 36° Jul 31 Aug 5 Aug 8 Aug 11 Aug 14 Aug 17 Aug 20 Aug 23 Aug 28

📍 Frost Dates for other nearby locations

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