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° | Oct 11 | Oct 18 | Oct 24 | Oct 29 | Nov 2 | Nov 6 | Nov 11 | Nov 17 | Nov 24 |
First 20° | Oct 4 | Oct 11 | Oct 16 | Oct 20 | Oct 24 | Oct 28 | Nov 2 | Nov 7 | Nov 14 |
First 24° | Sep 24 | Oct 1 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 22 | Oct 27 | Nov 3 |
First 28° | Sep 22 | Sep 27 | Sep 30 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 20 |
First 32° | Sep 11 | Sep 16 | Sep 19 | Sep 22 | Sep 24 | Sep 27 | Sep 30 | Oct 3 | Oct 7 |
First 36° | Sep 1 | Sep 6 | Sep 10 | Sep 13 | Sep 16 | Sep 19 | Sep 22 | Sep 26 | Oct 1 |
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 June 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 May 12, so we don't dare plant that early. We wait a few days and by May 22 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° | Apr 13 | Apr 8 | Apr 4 | Apr 1 | Mar 29 | Mar 26 | Mar 22 | Mar 19 | Mar 14 |
Last 20° | Apr 18 | Apr 14 | Apr 11 | Apr 8 | Apr 6 | Apr 3 | Apr 1 | Mar 29 | Mar 24 |
Last 24° | Apr 29 | Apr 24 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 8 | Apr 4 | Mar 30 |
Last 28° | May 13 | May 8 | May 4 | Apr 30 | Apr 27 | Apr 24 | Apr 21 | Apr 17 | Apr 12 |
Last 32° | May 23 | May 18 | May 15 | May 12 | May 9 | May 6 | May 3 | Apr 30 | Apr 25 |
Last 36° | Jun 6 | Jun 1 | May 28 | May 25 | May 22 | May 19 | May 16 | May 12 | May 7 |
Now that you know your frost dates, use our Garden Planting Calendar for Jordan, MN 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.