should I water my pots during this winter dry spell?

Personally I would not water as you say the rootball could freeze and kill the plant

hi there, welcome to GOY, sorry to throw a spanner in the works but I think you should water, infact was watching re-runs of gardeners world the other night, and the advice on there was yes to water during the winter season, just be careful when you do it. obviously avoid watering during periods of heavy frost, not much point in trying to water if the soil is frozen rock solid is there, and if the soil is frozen the roots will be as well anyway. You don't need to water a lot, little and often is best rather than a soaking every once in a while. but frost does cause the plant to dry out believe it or not. i have been watering mine, what i have done is go out on the milder mornings when not too much frost about and given some luke warm water, so any frozen bits get the chance to defrost and the plant can take the water in. it is best to do this earlier in the day, as the plant will have a chance of taking up the water, before freezing night time temps. also another tip, if you are worried that your pots may not be frost hardy, then you can wrap the outside of them with bubble wrap, i have found this very effective. hope this helps.

I have several outdoor Bonsai and very rarely water them, Evergreens other than Pines are best given some shelter, so when this current frost spell is over, water those which show dry surface. Leaf losing trees should be quite safe left to nature . I like to leave a few young seedling weeds on the surface, if the weeds droop then water . There has been no thaw at all in this part of North Hampshire for several days.

For what it's worth, I have had loads of plants in pots outdoors for donkey's years and have never watered them in the winter and have never lost a plant.
Bernard