The earliest snowfall on record for part of the viewing area occurred September 25, 1942.
The highest total in the viewing area was 4" at Wheatfield.
At West Lafayette, a the trace of snow on September 25, was the earliest on record by 12 days (beating October 6, 1906). No additional snow was recorded until November 10 with a trace. After that, there was none until November 28 (trace) before 3.0" fell on November 29.
The 1942-43 Fall-Spring snow season at West Lafayette ended up above normal with 33.1".
What is so interesting was not only the flakes at West Lafayette, but the duration of the chill so early. Seven conesutive mornings saw lows drop into the 30s (including two at 32). at this time was how quickly it warmed up after this chill. Once it did warm, it did so in a big way. After 38 on the morning of September 30, the high reached 80. September 30-October 3 saw highs +80.
Lows did not drop back into the 30s on a single night until October 23.
The storm system brought a large area of snowfall with up to 9" in Minnesota. Many areas of Iowa saw 4", while up to 4" fell in Illinois, 6.3" in Wisconsin & 8" in inland locations in the UP of Michigan.
The warm water of Lake Michigan & Superior led to mostly rain across far eastern Wisconsin & much of Michigan, even as the dynamic cooling would lead to snowfall. The mild air from the lake kept melting the flakes into rainfall, however.
Tree & power line damage occurred & the corn, soybean, wheat & barely to lima bean crops were bent or broken to the ground by the snow.
Widespread record cold followed. This affected the ripe or nearly ripe apples in orchards & the snow with the fruit weight caused many trees to snap.
For the event the cold surface temperatures show up like a sore thumb as the coldest in the Northern Hemisphere at the time, while record warmth occurred in Alaska to British Columbia & unusual warmth occurred over northern Greenland to the North Pole & over the Canadian Maritimes to Southeast U.S.
Temperatures at upper levels were record cold for the time of year, leading to the dynamic cooling & cold enough temperatures for crystal development so early in the Fall. With the sun angle, this also contributed to convective-like snowfall bands that led to quick accumulation despite very warm ground temperatures.
Note the unusually hot, dry, blocking ridge in Alaska & Yukon & Greenland to far eastern Canada.
Mid-level temperatures were also incredibly cold for the time of year, which contrasted with areas north, northwest & northeast & east of this location.
So, how did this all begin?
First, note how warm it was in mid-September. Temperatures aloft were well-above normal, & 80s to lower 90s dominated our area. The high on September 14 at West Lafayette was 91, for example. Lows on September 18 were only around 70 over the area.
A core of unusually cold air aloft with upper trough was found from Greenland to the Scandinavian countries.
A hot upper ridge was found over western & central Europe.
It appears that Pacific Typhoon #22 remnants (which followed #19, #20 & #21 in the same area!) merged with upper trough & led to a major storm over the Aleutians of Alaska. This led to record warm upper ridge to be pumped toward the Yukon & Alaska.
After this, all other typhoons (#23 to #33 tracked well southwest of this area that would dislodge cold).
This #22 & the other typhoon remnants & the major trough they produced in western Alaska led to the usually cold upper trough retrograding & being pulled southward.
For record cold in September, October or November, many times it is a Pacific typhoon developing into an extra-tropical Aleutian bomb that dislodges the chill.
1942 saw a very active western Pacific typhoon season. There were a total of 30.