Frost Dates: First and last frost dates for Jess Valley, 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 21, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around July 7, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 27, 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 25 Apr 16 Apr 9 Apr 3 Mar 29 Mar 24 Mar 18 Mar 11 Mar 2
Last 20° May 12 May 4 Apr 29 Apr 24 Apr 19 Apr 14 Apr 10 Apr 4 Mar 27
Last 24° May 29 May 23 May 19 May 16 May 12 May 9 May 5 May 1 Apr 25
Last 28° Jun 17 Jun 11 Jun 7 Jun 3 May 31 May 27 May 24 May 19 May 13
Last 32° Jul 6 Jun 30 Jun 25 Jun 21 Jun 18 Jun 14 Jun 10 Jun 6 May 30
Last 36° Jul 21 Jul 16 Jul 13 Jul 9 Jul 7 Jul 4 Jul 1 Jun 27 Jun 22

ℹ️ How to read these charts for the fall

As summer ends in Jess Valley, 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 August 28, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 10, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 23, 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 23 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 22 Oct 29 Nov 3 Nov 8 Nov 12 Nov 16 Nov 21 Nov 26 Dec 3
First 20° Oct 9 Oct 16 Oct 21 Oct 25 Oct 29 Nov 2 Nov 6 Nov 12 Nov 19
First 24° Sep 22 Sep 28 Oct 3 Oct 7 Oct 11 Oct 15 Oct 19 Oct 24 Oct 31
First 28° Sep 11 Sep 17 Sep 21 Sep 24 Sep 28 Oct 1 Oct 4 Oct 8 Oct 14
First 32° Aug 21 Aug 28 Sep 1 Sep 6 Sep 10 Sep 13 Sep 18 Sep 23 Sep 29
First 36° Aug 7 Aug 13 Aug 17 Aug 21 Aug 25 Aug 28 Sep 1 Sep 6 Sep 12

📍 Frost Dates for other nearby locations

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