Thanks for mentioning it. Great book.
This interpretation doesn’t make sense: there is no evidence that it was unusually cold when the compass “froze”, and anyway compass needles don’t freeze from cold (if they are liquid-filled, it’s typically alcohol with a freezing temperature below -100 F);
This is the only sensible interpretation of the quote from the OP.
I don’t think anybody is dumb enough to investigate Tunguska in the winter.
Perhaps the author meant that his compass needle pointed North, but that the needle refused to move away from that direction – most compasses have a bit of needle float. Imagine putting a compass near an MRI machine; the needle might lose some of its float.
Seriously, what book?
This sounded like a Tim Powers reference, to Declare to be specific. Sorry if I got that wrong. What were you referring to, then?
Baba Yaga, presumably: she may be a character in the book you read, but she’s a staple of Russian folklore and has been used by many authors.