Frost Dates: First and last frost dates for Des Moines Ap, IA
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 2.
- There is a 50% chance of being hit by a 32° frost starting around October 12
- You have a 80% chance of seeing 32° by October 22
- 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° | Nov 3 | Nov 10 | Nov 14 | Nov 18 | Nov 22 | Nov 26 | Nov 30 | Dec 4 | Dec 11 |
First 20° | Oct 29 | Nov 3 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 19 | Nov 22 | Nov 28 |
First 24° | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 15 | Nov 21 |
First 28° | Oct 9 | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 11 |
First 32° | Sep 26 | Oct 2 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 22 | Oct 27 |
First 36° | Sep 20 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 19 |
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 13. 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 21, so we don't dare plant that early. We wait a few days and by April 30 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° | Mar 29 | Mar 23 | Mar 19 | Mar 15 | Mar 11 | Mar 8 | Mar 4 | Feb 28 | Feb 22 |
Last 20° | Apr 10 | Apr 4 | Mar 30 | Mar 26 | Mar 23 | Mar 19 | Mar 15 | Mar 10 | Mar 4 |
Last 24° | Apr 13 | Apr 9 | Apr 6 | Apr 3 | Apr 1 | Mar 29 | Mar 27 | Mar 24 | Mar 19 |
Last 28° | Apr 18 | Apr 14 | Apr 12 | Apr 9 | Apr 7 | Apr 5 | Apr 2 | Mar 30 | Mar 27 |
Last 32° | May 2 | Apr 28 | Apr 25 | Apr 22 | Apr 20 | Apr 18 | Apr 15 | Apr 12 | Apr 8 |
Last 36° | May 13 | May 9 | May 5 | May 3 | Apr 30 | Apr 27 | Apr 25 | Apr 21 | Apr 17 |
Data is provided by the NOAA National Centers for Environmental Information.