Frost Dates: First and last frost dates for dubuque l&d, 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 1.
- There is a 50% chance of being hit by a 32° frost starting around October 11
- You have a 80% chance of seeing 32° by October 21
- 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 1 | Nov 7 | Nov 12 | Nov 15 | Nov 19 | Nov 23 | Nov 26 | Dec 1 | Dec 7 |
First 20° | Oct 25 | Oct 31 | Nov 4 | Nov 7 | Nov 10 | Nov 14 | Nov 17 | Nov 21 | Nov 27 |
First 24° | Oct 16 | Oct 22 | Oct 26 | Oct 29 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 19 |
First 28° | Oct 7 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Nov 1 | Nov 6 |
First 32° | Sep 26 | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 21 | Oct 26 |
First 36° | Sep 13 | Sep 18 | Sep 21 | Sep 24 | Sep 27 | Sep 30 | Oct 3 | Oct 6 | Oct 11 |
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 17. 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 23, so we don't dare plant that early. We wait a few days and by May 3 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° | Apr 1 | Mar 27 | Mar 23 | Mar 19 | Mar 16 | Mar 13 | Mar 9 | Mar 5 | Feb 28 |
Last 20° | Apr 4 | Mar 31 | Mar 28 | Mar 25 | Mar 23 | Mar 20 | Mar 18 | Mar 15 | Mar 10 |
Last 24° | Apr 14 | Apr 10 | Apr 7 | Apr 5 | Apr 2 | Mar 31 | Mar 29 | Mar 26 | Mar 22 |
Last 28° | Apr 18 | Apr 15 | Apr 13 | Apr 11 | Apr 9 | Apr 7 | Apr 5 | Apr 3 | Mar 30 |
Last 32° | May 2 | Apr 28 | Apr 25 | Apr 23 | Apr 20 | Apr 18 | Apr 15 | Apr 12 | Apr 8 |
Last 36° | May 17 | May 12 | May 9 | May 6 | May 3 | Apr 30 | Apr 27 | Apr 23 | Apr 18 |
Data is provided by the NOAA National Centers for Environmental Information.