Hi there, they should be absolutely fine so long as it isn't freezing cold, they are both hardy breeds, I know it's slightly different but I used to breed both budgies and canaries in a large outdoor aviary and in the winter the temperature could drop well below zero, if you are worried could you buy an oil filled radiator to take the chill off when really cold it would also help to use something like this to harden them off, really warm then cooler bit by bit until you switched radiator off altogether, cover the cage at night, this will help too.
Good luck.