Frost Dates: First and last frost dates for newport, 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 6. 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 April 12, so we don't dare plant that early. We wait a few days and by May 4 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° | Jan 10 | Dec 22 | -- | -- | -- | -- | -- | -- | -- |
| Last 20° | Jan 19 | Dec 31 | Dec 5 | -- | -- | -- | -- | -- | -- |
| Last 24° | Feb 16 | Jan 30 | Jan 17 | Jan 4 | Dec 20 | Nov 23 | -- | -- | -- |
| Last 28° | Mar 20 | Mar 8 | Feb 27 | Feb 18 | Feb 10 | Feb 2 | Jan 22 | Jan 2 | -- |
| Last 32° | May 5 | Apr 19 | Apr 8 | Mar 30 | Mar 21 | Mar 12 | Mar 2 | Feb 19 | Feb 4 |
| Last 36° | Jun 6 | May 26 | May 17 | May 10 | May 4 | Apr 27 | Apr 20 | Apr 12 | Mar 31 |
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 26.
- There is a 50% chance of being hit by a 32° frost starting around November 28
- You have a 80% chance of seeing 32° by December 31
- 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 26 | Jan 15 | -- | -- | -- | -- | -- | -- | -- |
| First 20° | Dec 11 | Jan 2 | Jan 31 | -- | -- | -- | -- | -- | -- |
| First 24° | Nov 26 | Dec 16 | Dec 31 | Jan 15 | Feb 2 | Mar 4 | -- | -- | -- |
| First 28° | Nov 12 | Nov 25 | Dec 4 | Dec 13 | Dec 21 | Dec 30 | Jan 10 | Jan 31 | -- |
| First 32° | Oct 9 | Oct 26 | Nov 8 | Nov 18 | Nov 28 | Dec 8 | Dec 19 | Dec 31 | Jan 18 |
| First 36° | Oct 6 | Oct 14 | Oct 20 | Oct 25 | Oct 30 | Nov 3 | Nov 8 | Nov 14 | Nov 22 |
Data is provided by the NOAA National Centers for Environmental Information.