My one and only (at least to my knowledge) episode of Afib was in December. I live at +/-7000 foot elevation in SW Colorado so it was cold. Probably in the mid 30F. I had been repairing the entry fence to my property and was bundled up in my Carhartt outfit and was sweating like the preverbal pig. Also not hydrating since it was so cold. In roughly 2 weeks I went from the picture of reasonably good health to having Afib. I am currently building a new perimeter fence and while it isn't really hot (+/- 85F) it is pretty humid because of the afternoon T-Storm build ups. I keep myself well hydrated.