Frost Dates: First and last frost dates for Mt Shasta, CA

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 5, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 17, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 5, 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° Mar 19 Mar 7 Feb 25 Feb 17 Feb 10 Feb 3 Jan 26 Jan 16 Jan 4
Last 20° Apr 10 Mar 31 Mar 24 Mar 18 Mar 12 Mar 6 Feb 28 Feb 21 Feb 10
Last 24° May 1 Apr 24 Apr 19 Apr 15 Apr 11 Apr 7 Apr 3 Mar 29 Mar 22
Last 28° May 19 May 13 May 8 May 4 Apr 30 Apr 26 Apr 22 Apr 17 Apr 11
Last 32° Jun 13 Jun 6 Jun 2 May 28 May 25 May 21 May 16 May 12 May 5
Last 36° Jul 5 Jun 29 Jun 25 Jun 21 Jun 17 Jun 14 Jun 10 Jun 5 May 30

ℹ️ How to read these charts for the fall

As summer ends in Mt Shasta, CA, 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 19, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 30, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By October 11, 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 October 11 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° Nov 14 Nov 23 Nov 29 Dec 4 Dec 9 Dec 14 Dec 19 Dec 25 Jan 3
First 20° Oct 29 Nov 6 Nov 11 Nov 16 Nov 20 Nov 24 Nov 29 Dec 4 Dec 12
First 24° Oct 20 Oct 25 Oct 30 Nov 2 Nov 5 Nov 9 Nov 12 Nov 16 Nov 22
First 28° Oct 7 Oct 12 Oct 16 Oct 19 Oct 22 Oct 25 Oct 28 Nov 1 Nov 6
First 32° Sep 13 Sep 19 Sep 23 Sep 27 Sep 30 Oct 3 Oct 7 Oct 11 Oct 17
First 36° Aug 31 Sep 5 Sep 9 Sep 13 Sep 16 Sep 19 Sep 22 Sep 26 Oct 2

📍 Frost Dates for other nearby locations

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