Frost Dates: First and last frost dates for paradise, ca
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 May 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 March 20, so we don't dare plant that early. We wait a few days and by April 7 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 28 | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 24° | Jan 23 | Jan 8 | Dec 19 | -- | -- | -- | -- | -- | -- |
| Last 28° | Feb 19 | Feb 6 | Jan 28 | Jan 20 | Jan 12 | Jan 3 | Dec 23 | Dec 2 | -- |
| Last 32° | Apr 14 | Mar 31 | Mar 22 | Mar 14 | Mar 6 | Feb 27 | Feb 19 | Feb 9 | Jan 27 |
| Last 36° | May 6 | Apr 26 | Apr 19 | Apr 13 | Apr 7 | Apr 2 | Mar 27 | Mar 20 | Mar 10 |
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 18.
- There is a 50% chance of being hit by a 32° frost starting around December 5
- You have a 80% chance of seeing 32° by December 21
- 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 1 | -- | -- | -- | -- | -- | -- | -- | -- |
| First 24° | Dec 25 | Jan 11 | Feb 3 | -- | -- | -- | -- | -- | -- |
| First 28° | Dec 2 | Dec 14 | Dec 23 | Dec 31 | Jan 7 | Jan 16 | Jan 28 | -- | -- |
| First 32° | Nov 9 | Nov 18 | Nov 24 | Nov 30 | Dec 5 | Dec 10 | Dec 15 | Dec 21 | Dec 30 |
| First 36° | Oct 29 | Nov 4 | Nov 8 | Nov 12 | Nov 16 | Nov 19 | Nov 23 | Nov 27 | Dec 3 |
Data is provided by the NOAA National Centers for Environmental Information.