I have just started thinking (which is not a good thing)
The temperature gauge measures the temperature after the Thermostat going to the radiator on my 323
On most cards the Temperature is measured before the Thermostat, on the engine side.

Now in your arctic conditions you could have the content in the radiator freeze up causing the car to overheat. I'm sure you know that better than me.

Maybe the cold outside air is keeping your temperature gauge up ?
I had this on Buick V6 motors that needed a long cycle of hot-cold-hot-cold before stabilising on our -5 C winter mornings. This was with a very quick responding gauge & I would think the MotoMeter gauge would be a lot more dampened, showing you tempertaures that are not current

The thermostat is also responsible for keeping the water circulation at a constant rate !
You can get the water overheating in the head & block if you run certain engines without thermostats, as the water circulates too quickly to absorb & transmit the heat.

I have been suffering with heat related issues for most of the past 19 years and realised it is not einfach...

__________________
Don't take life too seriously; no one gets out alive !