April showers bring May flowers, and after a late start to our spring, everything is finally beginning to bloom. With the trees and flowers blooming, and with the weather getting warmer, that means that many of you are ready to now plant your own flowers and vegetables, if you have not already done so. However, you don't want what you plant to get damaged by a frost or freeze, so that brings up the question: when does the last spring frost usually occur?
In the lower elevations in central Montana, the last spring frost typically occurs in mid to late May. In the higher elevations in central Montana, the last spring frost usually occurs in June.
For the major cities in central Montana, the average last spring frost date was calculated using data from 1991 to 2020. For the smaller towns and cities in central Montana, the average last spring frost date was calculated using data from 1981 to 2010. Since the average last spring frost date was calculated using older data for some of these towns and cities, that means that the actual average spring frost date may differ by a few days, but it is not going to differ enough to make a difference.
Once we get past the average last spring frost date, that means that we have a better chance of not seeing another frost versus seeing another frost. That does not mean we won't see another frost though, and in fact, the latest spring frost ever recorded for most locations is during the month of June.
If you are planning on planting sensitive flowers and vegetables, then I suggest at least waiting until after the average last spring frost date. If possible though, I would suggest waiting until at least Memorial Day weekend.
Although warmer temperatures are in the short-term forecast, the outlook for May 20 through May 26 is showing that we have a good chance to see below average temperatures and near to above average precipitation. This means that we are probably not done with the sub-freezing temperatures just yet. It is also possible that we could see more snow in some lower elevation locations before the month is over.
If you don't want to wait a few more weeks, or if you have already planted some sensitive plants, then please make sure you have a way to protect them on the colder nights, either by bringing them inside or covering them up.