apart from getting cold shaky hands, any reason why not?
Can you bleed brakes in cold weather or is it something best left for the warm?
It's pretty unpleasant... But otherwise fine.
Magura oil freezes about -15, DOT fluid about -20.
How far sub-zero are you?
And what brake fluid do the Canadians use?
Dot 4 freezes at -60c, though if it's old and wetted out that can change obviously just like the boiling point. Hydraulic mineral oil varies from product to product, frinstance Citroen LHM fluid has a pour point of -50c but will be thickening before that point.
But you're not likely to be working on the bike in those conditions I reckon.
After reading the answer from andrewh I had a quick check in the literature that is around here, and the "pour point" for Magura Blood is <50 C.
Just checking... Pay attention at the back there!!
Dagnabit!! Sorry 'bout the mistake. I Meant <-50°C... Today I'm only seeing the words on the screen 30 seconds after I'm typing them in here...? 😳