Welcome to 2018. Welcome to Mars.
How do these two statements connect?
With this image of the Dora cat with green laser eyes and a very nifty mat.

We came out of the night at -35C, the coldest night of the year 🙂 Pretty much the coldest of the last couple of weeks as well. So cold that the weather station battery failed… It was a 3v lithium that was just turning 5 years old. It was replaced yesterday afternoon, when the temperatures got to a somewhat reasonable -15C or so.
Seems to be working now, and through the cold night. In the last week the weather station pretty much shut down in the middle of the night and did not come back until after the sun had come up high enough to hit the solar panel.