Frost Dates: First and last frost dates for Chewelah, WA

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 July 10. 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 27, so we don't dare plant that early. We wait a few days and by June 14 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 15	Mar 8	Mar 2	Feb 26	Feb 21	Feb 17	Feb 12	Feb 7	Jan 30
Last 20°	Apr 7	Mar 30	Mar 25	Mar 20	Mar 16	Mar 11	Mar 7	Mar 1	Feb 22
Last 24°	Apr 28	Apr 22	Apr 17	Apr 13	Apr 10	Apr 6	Apr 2	Mar 29	Mar 22
Last 28°	May 17	May 11	May 7	May 3	Apr 29	Apr 26	Apr 22	Apr 17	Apr 11
Last 32°	Jun 3	May 28	May 24	May 20	May 16	May 13	May 9	May 5	Apr 28
Last 36°	Jul 10	Jul 1	Jun 24	Jun 19	Jun 14	Jun 8	Jun 3	May 27	May 18

How to read these charts for the fall

As your growing season comes to an end, the nightly temperatures for Chewelah, WA 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 September 3, and by September 27 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:

You have a small 20% chance of getting 32° by September 8.
There is a 50% chance of being hit by a 32° frost starting around September 17
You have a 80% chance of seeing 32° by September 27
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°	Oct 22	Oct 30	Nov 5	Nov 11	Nov 16	Nov 21	Nov 26	Dec 2	Dec 11
First 20°	Oct 5	Oct 11	Oct 15	Oct 18	Oct 22	Oct 25	Oct 29	Nov 2	Nov 8
First 24°	Sep 24	Sep 30	Oct 4	Oct 8	Oct 12	Oct 15	Oct 19	Oct 23	Oct 29
First 28°	Sep 14	Sep 19	Sep 23	Sep 26	Sep 29	Oct 2	Oct 6	Oct 9	Oct 15
First 32°	Sep 3	Sep 8	Sep 11	Sep 14	Sep 17	Sep 20	Sep 23	Sep 27	Oct 2
First 36°	Aug 23	Aug 27	Aug 31	Sep 3	Sep 6	Sep 9	Sep 12	Sep 15	Sep 20

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

Frost Dates for other nearby locations

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