I did 55 days beginning Feb 21, breaking the fast on Easter. “How was it” is a longer answer than I have time for (gotta get to bed). But as you specifically referenced winter I was often really chilled, mostly at night. I’m always chilled in the winter but fasting exacerbates that. A lot. On the coldest nights in my drafty 100+ y/o house I slept fully dressed in multiple layers + fleece hat and even gloves. I did a 10 day in the early fall and was fine in that regard. That said I would do it again without hesitation (and probably will - I have less obligations and a lighter work schedule in the winter).
The other thing was that I only slept about an hour or two at a time once I got into the heart of it. Looking back maybe that was the being chilled? Strangely enough I woke up earlier than my usual and felt MORE rested than usual. Always figured I could take a nap if I needed but I never did!
Best of luck to you.
The longest I have fasted in winter is 4 days. I have been intermittently fasting since I very young. Recently, for the past 3 months, I’ve had no alcohol, not that I’ve ever been much of a drinker. I feel no better and no worse! Moderation is key.