Frost Dates: First and last frost dates for Braintree, Massachusetts

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for Braintree, Massachusetts start to go down, and therefore every day that goes by increases the chance that you'll get frost. Your risk of frost really begins around October 2, and by October 23 you're almost certain to have received at least one frost event.

The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:

  1. You have a small 20% chance of getting 32° by October 6.
  2. There is a 50% chance of being hit by a 32° frost starting around October 15
  3. You have a 80% chance of seeing 32° by October 23
  4. Said another way, you have a 1 in 5 chance at making it to that day without a 32° night.
In the Fall
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
First 16° Nov 24 Nov 29 Dec 3 Dec 6 Dec 9 Dec 12 Dec 15 Dec 19 Dec 24
First 20° Nov 13 Nov 18 Nov 22 Nov 25 Nov 28 Dec 1 Dec 4 Dec 8 Dec 13
First 24° Oct 27 Nov 2 Nov 6 Nov 9 Nov 13 Nov 16 Nov 19 Nov 23 Nov 29
First 28° Oct 13 Oct 18 Oct 21 Oct 24 Oct 27 Oct 30 Nov 2 Nov 5 Nov 10
First 32° Oct 2 Oct 6 Oct 9 Oct 12 Oct 15 Oct 17 Oct 20 Oct 23 Oct 28
First 36° Sep 20 Sep 24 Sep 26 Sep 29 Oct 1 Oct 3 Oct 5 Oct 8 Oct 11

How to read these charts for the spring
As the growing season approaches, the days get longer, the weather begins to warm up, and the nights start being less cold. You're still getting frost, but the chance of nightly frosts gets less and less with each passing day. Eventually, the frost stops, and this is when your tender plants are fully safe. So, how do you plan for this? The probabilities on this page help you assess your risk of frost on any given day.

What's a safe temperature for tender plants? When the nightly temperature falls, frost can form, even above 32°, because the air is colder high above the ground and the frost can form up there and then fall down onto your garden and do some damage, even if it's 36° on the ground. So many factors come into play, including wind, concrete, houses, trees and other structures, etc etc etc. Because of all this, you might want to consider 36° as "the danger zone".

In your average springtime, you have a 90% chance that there will be no 36° nights by May 25. In other words, you can pretty much count on being safe from frost by that day. But we want to get those tomatoes in the ground as soon as possible, right? We see that there's still an 80% chance of 36° on May 5, so we don't dare plant that early. We wait a few days and by May 13 we are at the 50/50 point. At this point, we are close and we can start watching the weather forecast. If the upcoming week's forecast doesn't show below 40°, then it's probably okay to risk planting out your plants. If conditions change and a surprise frost does threaten, there's always things you can do to protect plants from frost.

In the Spring
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
Last 16° Mar 25 Mar 20 Mar 16 Mar 13 Mar 10 Mar 7 Mar 4 Mar 1 Feb 24
Last 20° Mar 31 Mar 27 Mar 24 Mar 21 Mar 19 Mar 17 Mar 14 Mar 12 Mar 8
Last 24° Apr 12 Apr 7 Apr 4 Apr 1 Mar 30 Mar 27 Mar 25 Mar 22 Mar 17
Last 28° Apr 27 Apr 23 Apr 20 Apr 18 Apr 15 Apr 13 Apr 11 Apr 8 Apr 4
Last 32° May 15 May 10 May 7 May 3 Apr 30 Apr 28 Apr 24 Apr 21 Apr 16
Last 36° May 25 May 21 May 18 May 15 May 13 May 10 May 8 May 5 May 1

Now that you know your frost dates, use our Garden Planting Calendar for Braintree, Massachusetts to know when to sow and transplant your various vegetable plants!

Data is provided by the NOAA National Centers for Environmental Information. Photography by Garden.org member TBGDN.

Sponsored by Victory Seed Company
Victory Seed Company The Victory Seed Company is family owned and operated, working to help fellow gardeners succeed by selling popular vegetable, herb and flower seeds. Since the 1990s they have been heavily involved with the preservation of rare, open-pollinated, heirloom seeds. Visit them at www.VictorySeeds.com.
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