Since we are going into a totally unrelated rabbits warren (I mean of course we are, there is a commuter posting to the thread... we are certainly going to get way off topic)
The climate of the Twin Cities is classified as hot-summer humid continental without dry season (KöppenDfa).[2] A feature of the humid continental climate in the United States is that weather can be unpredictable with extremes occurring in many phases of measurements. For example, the Twin Cities has a hotter all-time record high temperature of 108 °F (42 °C) than the entire state of Florida, despite being located nearly 1000 miles farther from the equator. Conversely, temperatures during the winter months are colder in the Twin Cities than in any other major metropolitan area in the continental United States, and are about equal to those in Anchorage, Alaska, which is around 1,000 miles (1,600 km) closer to the North Pole. The Twin Cities can also experience droughts, floods, and on average are windier than Chicago, Illinois (the "Windy City", although that is not the origin of the phrase).
Reference:
https://en.wikipedia.org/wiki/Climat...al_climatology
Nobody thinks Minneapolis is the only place that gets cold ... but there are few large cities (Canada has most of the others) that have extended periods of sub-zero (F) temps. Getting down to 0F/-18C for a night is cold ... but going 4-5 days without getting above 0F/-18C, that's definitely a different level of cold.
And since we are totally off topic, my buddies are up riding the Arrowhead 135 yesterday and today ... They start at International Falls (Frostbite Falls for all the Rocky and Bullwinkle fans), they have gone 2 weeks (14 days) without temps getting above 0F/-18C (I know, I know ... that was back when my grandpa was in diapers).
Lastly, there is somebody in this thread that is hyper-focused on one contributing factors to sub-zero black ice forming on road surfaces, and sure that single source wouldn't likely be enough to create enough ice to cause traction issues, yet it is clearly one of the contributing factors. This information was posted last week as a link, but I've copied text and added it to the tread to help those that just scrolled past the link:
How does black ice form throughout subzero temperatures? Anne Meyer, spokesperson for the Minnesota Department of Transportation, said the first aspect was the gentle snowfall.
“That was enough to give those tires something to melt when they were driving during the commute,” she said.
Then the cold quickly froze the melted snow, creating a thin, slick sheet on the pavement that drivers often can’t see. If the snow had fallen midday when the sun was in the sky, it likely would have stayed in liquid form until nightfall.
“If the snow would have happened overnight on the weekend, we would have had less traffic and as a result less areas of icy terrain,” Meyer added.
Bridges and overpasses are often trouble spots for black ice since cool air circulates above and below, chilling the pavement. Intersections can also be tricky.
“When traffic slows down a lot or even stops in some areas, even your exhaust, it can drip and those droplets then freeze and create black ice,” said Meyer.
Reference:
https://minnesota.cbslocal.com/2021/...-temperatures/
Going way back to the OP, if you're riding a bike during a sub-zero cold snap, you'd look out for black ice at stop lights, in the traffic lanes, where the stopped/idling cars create the conditions that will melt any water on the road surface (and add some exhaust vaper too). Moreover, the highways may be treated with better ice-melt chemicals, but you won't likely see that same treatment on the side streets where a person would ride a bike.