Frost Dates: First and last frost dates for Wallowa, 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 23, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around July 4, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 22, 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 6 Mar 27 Mar 20 Mar 15 Mar 9 Mar 4 Feb 26 Feb 19 Feb 10
Last 20° Apr 30 Apr 22 Apr 17 Apr 12 Apr 7 Apr 3 Mar 29 Mar 23 Mar 15
Last 24° May 14 May 8 May 4 May 1 Apr 28 Apr 25 Apr 22 Apr 18 Apr 13
Last 28° Jun 11 Jun 3 May 29 May 25 May 20 May 16 May 12 May 6 Apr 29
Last 32° Jul 4 Jun 27 Jun 21 Jun 17 Jun 13 Jun 9 Jun 4 May 30 May 23
Last 36° Jul 23 Jul 16 Jul 12 Jul 8 Jul 4 Jul 1 Jun 27 Jun 22 Jun 16

ℹ️ How to read these charts for the fall

As summer ends in Wallowa, 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 26, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 6, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 16, 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 16 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 12 Oct 19 Oct 24 Oct 28 Nov 1 Nov 5 Nov 9 Nov 14 Nov 21
First 20° Oct 1 Oct 6 Oct 10 Oct 13 Oct 16 Oct 19 Oct 22 Oct 26 Oct 31
First 24° Sep 16 Sep 22 Sep 25 Sep 29 Oct 2 Oct 5 Oct 8 Oct 12 Oct 17
First 28° Sep 5 Sep 9 Sep 12 Sep 15 Sep 18 Sep 20 Sep 23 Sep 26 Sep 30
First 32° Aug 21 Aug 26 Aug 30 Sep 2 Sep 6 Sep 9 Sep 12 Sep 16 Sep 21
First 36° Aug 6 Aug 11 Aug 15 Aug 18 Aug 20 Aug 23 Aug 26 Aug 29 Sep 3

📍 Frost Dates for other nearby locations

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