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 23. 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 16, so we don't dare plant that early. We wait a few days and by April 12 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. If conditions change and a surprise frost does threaten, there's always things you can do to protect plants from frost.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
Last 16° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
Last 20° | Dec 25 | -- | -- | -- | -- | -- | -- | -- | -- |
Last 24° | Feb 5 | Jan 23 | Jan 13 | Jan 3 | Dec 21 | -- | -- | -- | -- |
Last 28° | Mar 3 | Feb 18 | Feb 8 | Jan 30 | Jan 21 | Jan 12 | Jan 2 | Dec 16 | -- |
Last 32° | Apr 10 | Mar 27 | Mar 16 | Mar 7 | Feb 27 | Feb 18 | Feb 9 | Jan 30 | Jan 15 |
Last 36° | May 23 | May 9 | Apr 29 | Apr 20 | Apr 12 | Apr 4 | Mar 26 | Mar 16 | Mar 2 |
The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
First 16° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
First 20° | Jan 18 | -- | -- | -- | -- | -- | -- | -- | -- |
First 24° | Dec 8 | Dec 16 | Dec 22 | Dec 29 | Jan 7 | -- | -- | -- | -- |
First 28° | Nov 15 | Nov 24 | Dec 1 | Dec 7 | Dec 13 | Dec 19 | Dec 27 | Jan 11 | -- |
First 32° | Oct 27 | Nov 4 | Nov 10 | Nov 15 | Nov 20 | Nov 25 | Nov 30 | Dec 6 | Dec 15 |
First 36° | Oct 4 | Oct 14 | Oct 21 | Oct 27 | Nov 1 | Nov 7 | Nov 13 | Nov 20 | Nov 29 |
Now that you know your frost dates, use our Garden Planting Calendar for Stockton Ap, CA to know when to sow and transplant your various vegetable plants!
Data is provided by the NOAA National Centers for Environmental Information. Photography by Garden.org member TBGDN.