First Frost?

Recently, I have had to include a mention of a frost or freeze in the forecasts for some of my clients.  While these areas were in the far northern reaches of Wisconsin and Minnesota, it still brings into light that the first fall frost is just around the corner.  The predictability of frost is very important in regards to the harvesting of crops and the lives of your outdoor flowers and plants.  So, when do we typically see our first frost of the season?

According to the NCDC (National Climatic Data Center), the first frost for most of Minnesota and Wisconsin occur during the month of September, while areas like the eastern side of Wisconsin (south of Green Bay), southern Wisconsin, the Mississippi River Valley of the Coulee Region, and most of Iowa see their first frost in the first two weeks of October.  Granted that these are just the climatic averages, with the given year we're in, when could we see our first frost?  Let's find out!

Below is a listing of various cities and towns in Wisconsin along with three dates behind each.  The first column of dates represents a 10% probability of a 32 degree temperature (and thus frost) for that location before or on that date.  The second column of dates represents a 50% probability of a frost before or on that date, and the third column of dates represents a 90% probability of a frost before or on that date.

So for a place like Wausau, WI, there is a 10% chance of frost before Sept. 21st, a 50% chance before Oct. 2nd, and a 90% chance before Oct. 13th for the fall of 2010.

I hope this will give you some idea when to expect the first frost of the season in your area.  If there's a place I left out that you would like information on, just post a comment and I will do my best to find the data!

Happy Autumn!