Frost Dates: First and last frost dates for Crystal City, TX
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 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 February 13, so we don't dare plant that early. We wait a few days and by March 1 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° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 20° | Jan 12 | Jan 1 | Dec 19 | -- | -- | -- | -- | -- | -- |
| Last 24° | Feb 3 | Jan 23 | Jan 13 | Jan 4 | Dec 23 | -- | -- | -- | -- |
| Last 28° | Feb 23 | Feb 12 | Feb 4 | Jan 28 | Jan 22 | Jan 15 | Jan 7 | Dec 27 | -- |
| Last 32° | Mar 20 | Mar 9 | Mar 1 | Feb 23 | Feb 16 | Feb 10 | Feb 4 | Jan 27 | Jan 16 |
| Last 36° | Mar 25 | Mar 16 | Mar 10 | Mar 5 | Mar 1 | Feb 24 | Feb 19 | Feb 13 | Feb 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 November 19.
- There is a 50% chance of being hit by a 32° frost starting around December 6
- You have a 80% chance of seeing 32° by December 23
- 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° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| First 20° | Dec 25 | Jan 5 | Jan 21 | -- | -- | -- | -- | -- | -- |
| First 24° | Dec 11 | Dec 23 | Jan 1 | Jan 11 | Jan 24 | -- | -- | -- | -- |
| First 28° | Nov 30 | Dec 8 | Dec 14 | Dec 19 | Dec 24 | Dec 29 | Jan 4 | Jan 12 | -- |
| First 32° | Nov 10 | Nov 19 | Nov 25 | Dec 1 | Dec 6 | Dec 11 | Dec 17 | Dec 23 | Jan 1 |
| First 36° | Nov 5 | Nov 11 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 3 | Dec 9 |
Data is provided by the NOAA National Centers for Environmental Information.