I'm on the northeast coast of America. Today, it's brass monkeys out there: minus 8 degrees centigrade with the wind chill factored in. I'm about to go on my daily 3-mile brisk walk. Does the outside temperature make a difference to calories burned during this kind of exercise? Cases: Very cold like today. Temperate, as in spring/autumn. Very hot, as it can be here in the summer (in the high 30s centigrade). In all these cases I am assuming appropriate clothing. When warm enough, "gym clothes." During cold periods, very covered up, including warm trousers, down-filled coat, and low-temperature-rated balaklava and gloves.