Frost Dates: First and last frost dates for Quincy, 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 28, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around July 9, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 26, 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 2 Feb 17 Feb 6 Jan 27 Jan 17 Jan 6 Dec 23 Dec 2
Last 20° Apr 17 Apr 1 Mar 21 Mar 11 Mar 2 Feb 20 Feb 11 Jan 30 Jan 14
Last 24° May 20 May 7 Apr 27 Apr 18 Apr 11 Apr 3 Mar 25 Mar 16 Mar 2
Last 28° Jun 1 May 24 May 18 May 14 May 9 May 4 Apr 29 Apr 24 Apr 16
Last 32° Jul 10 Jul 1 Jun 24 Jun 18 Jun 13 Jun 7 Jun 2 May 26 May 16
Last 36° Jul 28 Jul 21 Jul 16 Jul 12 Jul 9 Jul 5 Jul 1 Jun 26 Jun 20

ℹ️ How to read these charts for the fall

As summer ends in Quincy, 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 21, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 8, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 26, 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 26 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 24 Nov 8 Nov 18 Nov 27 Dec 6 Dec 15 Dec 24 Jan 5 Jan 22
First 20° Oct 7 Oct 16 Oct 23 Oct 29 Nov 4 Nov 9 Nov 15 Nov 22 Dec 2
First 24° Sep 24 Oct 2 Oct 8 Oct 13 Oct 17 Oct 22 Oct 27 Nov 1 Nov 9
First 28° Sep 5 Sep 13 Sep 19 Sep 24 Sep 29 Oct 3 Oct 8 Oct 14 Oct 22
First 32° Aug 11 Aug 21 Aug 28 Sep 3 Sep 8 Sep 14 Sep 19 Sep 26 Oct 6
First 36° Jul 31 Aug 7 Aug 13 Aug 18 Aug 22 Aug 27 Sep 1 Sep 7 Sep 15

📍 Frost Dates for other nearby locations

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