I am not an experienced overseas traveler. Had a wonderful RS tour that included Wales in June 2014. Don't want to wait until next year to go again. Trying to make up for lost time -- so many decades I let slip by without international travel. I want to go back as soon as I can and also hopefully spend less money than a trip in "fair" weather. I live in an area of the U.S. with real winters (Western NY) and I am outside and active all year round. Initial climate research looks like Wales won't be worse than where I live and play in Nov. and Dec., though I know it could vary by where you are in Wales. I envision staying for about 7 days in one or two spots -- an inn or National Trust cottage, taking day trips. Am researching what sites are open at that time of year (many have no or restricted times of course). Will figure out how to get to Wales, some combo of flying to London or Manchester, then a train, then a rental car. But what about going that time of year? Biggest hassle I see is trying to pack light but have the proper clothing for being outside in late fall/early winter. Ann.
You are correct about not worrying about the cold. It is very unlikely to get below freezing (0°C) in November or December, except up in the mountains.
But, what the British weather is famous for in November and December is grey, damp drizzley days with low cloud. The amount of rain falling will not be high, it will just take many hours longer for the same amount. On many days low cloud will cover the hills.
The days will also be a lot shorter than you are used to because it is a lot further north. Sunrise in December is around 07:30, sunset is just before 4pm, expect it to start getting dark around 16:30.
For example for Holyhead:
Temperature Average High: Jun 17.1°, Jul 18.8, Nov 11.1°, Dec 8.7° - not cold
rain Jun 53.5 cm, Jul 54.0 cm, Nov 103.5 cm, December 90.6 cm - a lot wetter
Average Sunshine hours: Jun 207.8 hours, Jul 201.1, Nov 63.6, Dec 51.6 - less than 2 hours sunshine per day in December!
That said, it can be very beautiful in a grey sort of way.
I've read that there are some wonderful Christmas Markets in Wales... and there could be some great special holiday events at some of the national trust locations...be sure to check the Welsh historical locations sites also. Check with the Universities and Churches for concerts. You should start making your reservations now.
No lake effect snow, very rare deep cold.
Plan on plenty of low pressure fronts coming off the Atlantic. A basic rule at that time of year is that if the weather is warm it is likely to be wet; if it is cold it is likely to be clear.
I disagree about the darkness though. If it is sunset at 4pm it will be pretty dark outside around 3:30 or 3:00 not 4:30. At that time of year there is no twilight. Plan on needing interior lights from 2:30 on an overcast day or 3pm on a clear day. Remember that the sun is in the south.
Loved traveling this area in nov, dec, and jan....benefits...cheaper, less tourists... I do not mind the shorter days and I love the lighting at this time of year. It is beautiful for photography. Had a number of days where it was warm and only needed a sweater, some days needed layers and hat and gloves. I think it is so interesting to travel in the off season. You get a much more intimate look at a location. There is never a bad time to travel:)
Thanks for all your observations and thoughts! I hadn't even considered the shorter hours of daylight (note I didn't say "sunlight" or "sunshine"!) and that's important to consider. Wonderful in late spring/early summer to have those long days; different in late fall. But I lived in Maine for eight years and it got dark very early in the late fall/early winter too, due to being so far north AND east. I looked at a couple of sunrise/sunset charts for where I live now and for Wales and it's about 20-30 minutes different. I can deal with that. I have the proper clothes and like to be outside in most weather. Thanks again! Ann.
Although the weather is unlikely to impede you too much, if you intend visiting Wales in the winter, do your homework first on the places you want to visit, their opening hours, and the public transport in winter to get to them (if you're not driving). Many visitor locations run reduced opening hours during the winter, or even close completely - so plan ahead to avoid disappointment. Also, public transport timings and frequency can change, so check that out too.