Does a person burn more calories in colder/hotter temperatures? If their daily routine is the same with the only difference being the temperature? Based apon nothing, I assume a person burns more calories during the winter and hottest parts of summer.
WAG. The rate of heat loss through a boundry depends on the temperature difference across the boundry. So in winter the heat loss would be high and that energy loss would need to be made up by additional food input. Of course, clothing or fur or feathers reduce the heat loss by maintaining a higher skin temperature.
In summer the air temperature is high but the skin is cooled by evaporation. However, clothing reduces the skin area exposed to the air for evaporation so I would suppose that winter would result in a need for a higher calorie input.
It seems to me that very few farmers in cold climates raise animals for slaughter in the winter. I would suspect this is because the weight gain is lower because so much of the food goes into maintaining body temperature and not into increased weight.
You burn a lot more Kcals in cold weather.
NUTRITIONAL ADVICE FOR OPERATIONS IN A COLD ENVIRONMENT
For more on cold response see: Human Physiological Responses to Cold Stress and Hypothermia
When I took a cold weather camping course, we learned about this. On a weekend campout in January (I’m in the chicago area) we were advised to consume 3000-4000 calories a day, because we would be burning so much more staying out in the cold for three days straight.
We ate a lot of snickers bars.