Frost Dates: First and last frost dates for Crater Lake Nps Hq, 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 21, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before July 14, 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 26 May 19 May 14 May 9 May 5 May 1 Apr 26 Apr 21 Apr 14
Last 20° Jun 13 Jun 6 Jun 1 May 28 May 24 May 20 May 16 May 11 May 4
Last 24° Jun 26 Jun 20 Jun 16 Jun 12 Jun 9 Jun 5 Jun 2 May 28 May 23
Last 28° Jul 16 Jul 9 Jul 5 Jul 1 Jun 27 Jun 23 Jun 19 Jun 15 Jun 8
Last 32° Jul 25 Jul 20 Jul 17 Jul 14 Jul 11 Jul 8 Jul 5 Jul 2 Jun 27
Last 36° Jul 31 Jul 28 Jul 25 Jul 23 Jul 21 Jul 19 Jul 17 Jul 14 Jul 11

ℹ️ How to read these charts for the fall

As summer ends in Crater Lake Nps Hq, 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 6, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By August 19, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 1, 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 1 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 15 Oct 23 Oct 28 Nov 1 Nov 5 Nov 9 Nov 14 Nov 19 Nov 26
First 20° Oct 2 Oct 9 Oct 15 Oct 19 Oct 23 Oct 27 Oct 31 Nov 5 Nov 12
First 24° Sep 9 Sep 16 Sep 21 Sep 26 Sep 30 Oct 4 Oct 8 Oct 13 Oct 20
First 28° Aug 22 Aug 30 Sep 4 Sep 9 Sep 13 Sep 18 Sep 22 Sep 28 Oct 6
First 32° Jul 31 Aug 6 Aug 11 Aug 15 Aug 19 Aug 23 Aug 27 Sep 1 Sep 7
First 36° Jul 31 Aug 3 Aug 6 Aug 8 Aug 11 Aug 13 Aug 16 Aug 19 Aug 23

📍 Frost Dates for other nearby locations

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