The freeze is coming

- October is here, the leaves are changing, and now it’s time for the temperatures to really start to fall… back below freezing.  The entire region typically gets a freeze before the month is over, but for Minnesota, it’s usually sooner rather than later.  In the average fall, the entire state has experienced a freeze by the end of the first week (which you can see in the image below), with a killing freeze (25°) likely by Halloween. 

But this year has been a little different, and a little behind.  More than half the state has been frost and freeze free… until now.  Conditions are setting up to give much of the area a hard free come Friday night.  Here are the spots that have already seen the freeze mark across the Upper Midwest, with their color showing what week they hit 32.

Northern parts of the state were right on target with their annual fall freeze, but central and much of southern Minnesota continues to lag behind.

To get what’s called a hard freeze, temperatures need to be at or below 32° for at least 3 consecutive hours OR hit 28° at any point in the night.  A hard freeze will cause damage to many sensitive plants and various types of vegetation that haven’t gone dormant for the winter.  When this occurs, trees that have not lost their leaves in entirety expedite the process so they don’t receive any further damage.  So how cold will it get Friday night?

Well, conditions look pretty favorable for a hard freeze with much of the area experiencing clearish skies and calmish winds which allows the cold dense air to sink to the surface overnight.  But just how cold we get is a tough call.  For example, here is a look at 3 different forecasting computer models that shows temperatures overnight Friday.