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° | Nov 14 | Nov 19 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 9 | Dec 15 |
| First 20° | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 4 |
| First 24° | Oct 25 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 23 |
| First 28° | Oct 7 | Oct 13 | Oct 18 | Oct 23 | Oct 26 | Oct 30 | Nov 1 | Nov 5 | Nov 10 |
| First 32° | Sep 28 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 23 | Oct 29 |
| First 36° | Sep 16 | Sep 20 | Sep 23 | Sep 27 | Sep 30 | Oct 1 | Oct 4 | Oct 7 | Oct 13 |
What's a safe temperature for tender plants? Frost can form on plants even when the air temperature is above 32°. This happens because of radiative cooling. On clear nights, surfaces like leaves and the ground radiate their heat to the cold night sky. As dew forms on these surfaces, those water droplets continue losing heat and can reach freezing even when the surrounding air is a few degrees warmer. This is why frost is more common on clear, calm nights (clouds act as insulation against this heat loss) and why low-lying areas frost first, since the coldest air settles near the ground. So many factors come into play, including wind, cloud cover, nearby structures, trees, and terrain. 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 28. 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 2, so we don't dare plant that early. We wait a few days and by May 13 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 5 | Apr 2 | Mar 30 | Mar 27 | Mar 24 | Mar 21 | Mar 18 | Mar 14 | Mar 9 |
| Last 20° | Apr 12 | Apr 8 | Apr 4 | Apr 2 | Apr 1 | Mar 30 | Mar 26 | Mar 22 | Mar 17 |
| Last 24° | Apr 23 | Apr 18 | Apr 15 | Apr 12 | Apr 8 | Apr 6 | Apr 3 | Apr 1 | Mar 28 |
| Last 28° | May 7 | May 2 | Apr 29 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 12 | Apr 7 |
| Last 32° | May 18 | May 11 | May 7 | May 4 | May 2 | Apr 30 | Apr 26 | Apr 23 | Apr 19 |
| Last 36° | May 28 | May 24 | May 20 | May 16 | May 13 | May 9 | May 6 | May 2 | Apr 28 |
Now that you know your frost dates, use our Garden Planting Calendar for Binghamton Greater Ap, NY 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.
The Victory Seed Company is family owned and operated, working to help fellow gardeners succeed by selling popular vegetable, herb and flower seeds. Since the 1990s they have been heavily involved with the preservation of rare, open-pollinated, heirloom seeds. Visit them at www.VictorySeeds.com.