Frost Dates: First and last frost dates for St Bernard, LA
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 March 27. 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 February 15, so we don't dare plant that early. We wait a few days and by March 3 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° | Dec 27 | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 20° | Jan 16 | Jan 1 | -- | -- | -- | -- | -- | -- | -- |
| Last 24° | Feb 8 | Jan 27 | Jan 18 | Jan 8 | Dec 28 | -- | -- | -- | -- |
| Last 28° | Feb 25 | Feb 16 | Feb 9 | Feb 3 | Jan 27 | Jan 20 | Jan 9 | -- | -- |
| Last 32° | Mar 9 | Mar 1 | Feb 23 | Feb 18 | Feb 13 | Feb 9 | Feb 3 | Jan 28 | Jan 18 |
| Last 36° | Mar 27 | Mar 19 | Mar 13 | Mar 8 | Mar 3 | Feb 26 | Feb 21 | Feb 15 | Feb 6 |
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 November 29.
- There is a 50% chance of being hit by a 32° frost starting around December 18
- You have a 80% chance of seeing 32° by January 8
- 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° | Jan 14 | -- | -- | -- | -- | -- | -- | -- | -- |
| First 20° | Jan 5 | Jan 20 | -- | -- | -- | -- | -- | -- | -- |
| First 24° | Dec 20 | Dec 29 | Jan 6 | Jan 13 | Jan 23 | -- | -- | -- | -- |
| First 28° | Dec 6 | Dec 14 | Dec 21 | Dec 27 | Jan 2 | Jan 9 | Jan 19 | -- | -- |
| First 32° | Nov 18 | Nov 29 | Dec 6 | Dec 12 | Dec 18 | Dec 24 | Dec 31 | Jan 8 | Jan 20 |
| First 36° | Nov 7 | Nov 15 | Nov 21 | Nov 26 | Dec 1 | Dec 6 | Dec 11 | Dec 17 | Dec 26 |
Data is provided by the NOAA National Centers for Environmental Information.