Frost Dates: First and last frost dates for oakridge fish hatchery, or
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 June 16. 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 12, so we don't dare plant that early. We wait a few days and by May 26 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.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
Last 16° | Feb 7 | Jan 24 | Jan 12 | Dec 30 | Dec 8 | -- | -- | -- | -- |
Last 20° | Feb 15 | Feb 4 | Jan 27 | Jan 19 | Jan 12 | Jan 4 | Dec 26 | Dec 8 | -- |
Last 24° | Mar 12 | Feb 28 | Feb 19 | Feb 12 | Feb 5 | Jan 29 | Jan 22 | Jan 12 | Dec 29 |
Last 28° | Apr 21 | Apr 11 | Apr 4 | Mar 29 | Mar 24 | Mar 19 | Mar 13 | Mar 6 | Feb 24 |
Last 32° | May 15 | May 8 | May 2 | Apr 28 | Apr 24 | Apr 20 | Apr 16 | Apr 10 | Apr 3 |
Last 36° | Jun 16 | Jun 9 | Jun 4 | May 30 | May 26 | May 22 | May 17 | May 12 | May 5 |
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 October 4.
- There is a 50% chance of being hit by a 32° frost starting around October 14
- You have a 80% chance of seeing 32° by October 25
- Said another way, you have a 1 in 5 chance at making it to that day without a 32° night.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
First 16° | Dec 12 | Dec 29 | Jan 13 | Jan 30 | -- | -- | -- | -- | -- |
First 20° | Nov 28 | Dec 11 | Dec 20 | Dec 28 | Jan 6 | Jan 15 | Jan 28 | -- | -- |
First 24° | Nov 6 | Nov 18 | Nov 26 | Dec 3 | Dec 10 | Dec 17 | Dec 24 | Jan 2 | Jan 16 |
First 28° | Oct 15 | Oct 26 | Nov 2 | Nov 8 | Nov 14 | Nov 20 | Nov 26 | Dec 4 | Dec 14 |
First 32° | Sep 28 | Oct 4 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 21 | Oct 25 | Oct 30 |
First 36° | Sep 8 | Sep 15 | Sep 20 | Sep 24 | Sep 28 | Oct 2 | Oct 6 | Oct 11 | Oct 18 |
Data is provided by the NOAA National Centers for Environmental Information.