Frost Dates: First and last frost dates for Orleans, 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 15. 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 April 16, so we don't dare plant that early. We wait a few days and by April 27 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° | Jan 4 | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 20° | Jan 28 | Jan 8 | -- | -- | -- | -- | -- | -- | -- |
| Last 24° | Feb 13 | Feb 3 | Jan 26 | Jan 19 | Jan 11 | Jan 2 | Dec 16 | -- | -- |
| Last 28° | Mar 14 | Feb 27 | Feb 16 | Feb 7 | Jan 29 | Jan 20 | Jan 11 | Dec 30 | Dec 12 |
| Last 32° | Apr 29 | Apr 17 | Apr 8 | Mar 31 | Mar 24 | Mar 17 | Mar 9 | Feb 28 | Feb 16 |
| Last 36° | May 15 | May 9 | May 4 | May 1 | Apr 27 | Apr 24 | Apr 20 | Apr 16 | Apr 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 October 29.
- There is a 50% chance of being hit by a 32° frost starting around November 17
- You have a 80% chance of seeing 32° by December 6
- 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° | Feb 4 | -- | -- | -- | -- | -- | -- | -- | -- |
| First 20° | Dec 29 | Jan 19 | -- | -- | -- | -- | -- | -- | -- |
| First 24° | Nov 18 | Dec 1 | Dec 11 | Dec 21 | Dec 31 | Jan 13 | -- | -- | -- |
| First 28° | Nov 5 | Nov 17 | Nov 25 | Dec 2 | Dec 9 | Dec 16 | Dec 23 | Jan 2 | Jan 21 |
| First 32° | Oct 19 | Oct 29 | Nov 5 | Nov 12 | Nov 17 | Nov 23 | Nov 29 | Dec 6 | Dec 16 |
| First 36° | Oct 7 | Oct 15 | Oct 22 | Oct 27 | Nov 1 | Nov 6 | Nov 11 | Nov 17 | Nov 26 |
Data is provided by the NOAA National Centers for Environmental Information.