Kane County’s weather this week is a little bit of a “fire and ice” situation.
Even as we face a Red Flag Warning for fire danger, Kane County is also looking at what’s likely to be the first freeze of the fall season on Thursday night (Oct. 15, 2020).
It’s important to note that a freeze is different than frost. We’ve had plenty of frost in recent days — that light covering ice crystals that you might see on grass in the early morning.
Frost happens when the atmosphere is above freezing and the ground is below freezing.
A freeze can happen when the surface air temperature falls to 32 degrees or below; frost may or may not form. A light freeze (between 32 and 29 degrees F) can kill tender plants.
A moderate freeze (between 28 and 25 degrees), sometimes called a hard freeze, can cause wide destruction to most plants.
What we’re looking at in the Kane County forecast on the National Weather Service Chicago site is a low temperature of 30 degrees on Thursday night. That may or may not be “killing freeze,” but gardeners will want to take note.
Average First Freeze
Kane County is on par if we do see a first freeze Thursday.
According to statistics posted by the National Weather Service Chicago, Kane County’s first freeze generally comes between Oct. 11 and Oct. 20.
The earliest autumn freeze was in 1995, when we hit 32 degrees on Sept. 22.
The latest freeze goes back to 1931, when we hit 30 degrees on Nov. 24.
As recently as 2016, Rockford posted its latest first freeze ever — on Veterans Day, and Chicago clocked its first freeze a day later, on Nov. 12, 2016.
The 2016 Chicago freeze didn’t set a record, however. In fact, Chicago recorded a later first freeze in 1975 as well as that 1931 record.
Remember Halloween 2019?
Remember the big snow we got last year on Halloween?
The official snowfall for Chicago on Oct. 31, 2019, was 3.4 inches, observed at Chicago O’Hare International Airport.
That single event made October 2019 the second snowiest October on record in Chicago with 4.6 inches falling — not far behind 6.3 inches in 1989.
What Gardeners Should Do
Generally speaking, gardeners should be aware of the first freeze, because it signals the time to take some action.
Examples include clearing the summer vegetable garden, planting new trees and shrubs, getting rid of weeds, covering tender plants (such as azaleas, rhododendrons, and smaller evergreens), prune back dead mulch and clear out water lines.
SOURCE: National Weather Service Chicago