The fact of the matter is I don't know exactly how cold it got at my house today.

The mercury thermometer on our porch only goes down to -30 degrees Fahrenheit (-34.4 Celsius). The digital thermometer in our backyard weather station bottoms out at -40 Fahrenheit (-40 Celsius).

For roughly two hours on Wednesday this thermometer registered -40.0, even, as the actual air temperature descended below that level to depths unknown.

What I do know, however, is that beyond a certain point the only thing you feel outside is pain.

My family moved to rural Minnesota in 2016 from Baltimore, and our first winter late that year brought my first exposure to sustained temperatures below zero.

In those days I came to the belief all temperatures below zero are essentially the same in terms of how they're experienced.

Ten below is bitter cold. Twenty below is also bitter cold. Therefore, by the transitive property, ten below and twenty below are the same.

I now know this to be false.

There are, in fact, endless variations of cold, pain and suffering that a person may experience on the long, dark slide from 0 to -40 and beyond.

Down to about twenty below things aren't so bad, honestly. You need to hustle a little bit on your way out to the car, and you've got a few seconds to futz with your keys at the door before the cold starts to dig into your skin.

You get a kind of thermal grace period between when you first expose your skin to the air and when the cold starts to bite.

As long as it's above -20 Fahrenheit (-30 Celsius), it's not uncommon to see Minnesotans out and about without a hat or gloves, or even in shorts. I used to think they were insane, but having lived here for several winters I now understand that if you're just making a quick jaunt out to the mailbox or into a store, it's overkill to go through the hassle of suiting up all the way.

Rule of thumb: if the amount of time you expect to spend outdoors is less than the amount of time it will take to get your coat, hat, mittens and scarf on, you can just dash out of the house in whatever you're wearing.

Below -20, however, this calculus changes. Beyond this threshold the thermal grace period shrinks rapidly and disappears altogether.

By about -30 the cold doesn't feel like cold anymore - it's just pure, unadulterated pain, a sharp, burning sensation.

After a few moments the burning gives way to a deep, dull ache that feels like it's radiating from your bones.

I've never been brave and/or dumb enough to test what comes after the ache but my assumption is that it's deeply unpleasant and possibly irreversible.

Wind adds a separate dimension to the experience of the cold up here. Starting around -20 the wind stops registering as a tactile sensation and is experienced primarily as a more urgent kind of pain.

At -30 it's like a hot iron on your exposed skin. At -40 it's a burning scream.

At the moment there's about a 100-degree Fahrenheit (55-degree Celsius) temperature differential between the air in our house and the air outside, which causes some weird things to happen.

In the middle of the night, we hear thunderous creaks and pops emanating from the walls of the house as the building materials contract and settle.

We've got a thick layer of ice growing on the interiors of our double-paned windows. Sometimes our doors get frozen shut, and when we open them it lets in a blast of frigid air that sucks all the moisture out of the house and turns it into a rolling fog.

Most of the homes around here are very well insulated, so we don't worry too much about frozen indoor pipes. Last year, however, part of the water main on our street froze solid.

For several months one of our neighbors had to run a hose to someone else's house to get water. The city instructed the rest of us on the block to keep a faucet running at all times (they credited us the difference on our water bills).

After Wednesday the temperature is forecast to rise again - by Thursday we'll be back in the single digits below zero, which will be a welcome relief after several days below negative 20. I may even put my shorts on to celebrate.

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