as long as your birds have been doing an hour at home and you dont go to far 25 miles max after a few at 12 or miles you will not have a problem shasha been training december and january for a few years now with latebreds that are only going four or five races then stopped bit of sunshine and good viz and wind not to strong i dont bother about temp and if there fit it dont bother them a 30 min fly is nothing to a pigeon imo