My Dad had a winter allergy.
That's what my Mom told me when I was young.
He was the best Dad any kid could ever hope for. Every single minute he wasn't working or doing something that Mom asked him to do, he spent time with me. He was a heavy smoker and rather overweight, so we did not play in the playground much. I remember he always ran out of breath and couldn't keep up with me running in circles yelling 'Catch me, Daddy!'. So we mostly played together indoors.