Frost Dates: First and last frost dates for Anvil Rch, AZ
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 April 13. 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 25, so we don't dare plant that early. We wait a few days and by March 16 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° | Dec 26 | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 24° | Feb 1 | Jan 13 | Dec 27 | Nov 30 | -- | -- | -- | -- | -- |
| Last 28° | Feb 22 | Feb 9 | Jan 31 | Jan 23 | Jan 16 | Jan 8 | Dec 30 | Dec 20 | Nov 29 |
| Last 32° | Mar 18 | Mar 8 | Feb 28 | Feb 22 | Feb 16 | Feb 10 | Feb 4 | Jan 27 | Jan 17 |
| Last 36° | Apr 13 | Apr 3 | Mar 27 | Mar 21 | Mar 16 | Mar 10 | Mar 4 | Feb 25 | Feb 15 |
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 16.
- There is a 50% chance of being hit by a 32° frost starting around November 29
- You have a 80% chance of seeing 32° by December 12
- 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° | Jan 7 | -- | -- | -- | -- | -- | -- | -- | -- |
| First 24° | Dec 17 | Jan 4 | Jan 22 | -- | -- | -- | -- | -- | -- |
| First 28° | Nov 23 | Dec 2 | Dec 9 | Dec 14 | Dec 20 | Dec 26 | Jan 1 | Jan 11 | -- |
| First 32° | Nov 9 | Nov 16 | Nov 21 | Nov 25 | Nov 29 | Dec 3 | Dec 7 | Dec 12 | Dec 19 |
| First 36° | Nov 4 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Nov 30 | Dec 5 |
Data is provided by the NOAA National Centers for Environmental Information.