May not be applicable but I do cold baths: 20-30 minute soaks in 50 deg F water. I usually do them daily after a sauna session. The baths will slow my heart rate significantly - a vagal response. Noticed today, the third day of a fast, that I could feel some PAC's upon entering the water. The fasting is pertinent as my core temp usually drops as I get 3 or more days into fasts (my habit is to fast 5 consecutive days of every 14). So today I decided to pay attention to the PAC signals I was getting and abort the fast early and go for a walk in shorts, sandals & a t-shirt in the 25 deg Colorado morning, this did not provoke PAC's. As air is much less conductive of heat than water, 25 deg air doesn't have the same impact as 50 deg water.
In any case, the cold air might be provoking a vagal response for you.
George
