I would say that it probably would be okay if you got the chicks now!
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Going from what would normally be just-off-heat, indoor brooder temperatures out into lows of -10C could be pretty rough unless you can make the transition a more gradual one. I had two late fall chicks last year and I went through the winter only letting them be outside during the warmest part of the day and had to still give them a plate-type heater during the colest parts months (although my area does get colde than yours; I simply didn't take them outside at all at its worst). Cold tolerance issues can also hit fast and don't affect all individuals the same way. You might get lucky and have a bunch that handle it, or you could have some that do and some that don't, etc. Those two chicks I had were a cockerel and a pullet, and a couple times I put them outside when I thought it's be fine and returned to check on them an hour later to find out that the cold was just a bit too much for the cockerel with his comb and wattles going purple. The pullet was hardier but she also has some dark pigment on her comb and wattles so it would've been hard to tell if she was being affected. Personally I would wait until the temperatures are certain to be warmer to avoid a potentially complicated situation if the chicks don't adapt well.Sometimes -10 C.