We were there for the New Year a couple of years ago. It was warm and comfortable to walk around in t/shirts etc, in the late evening you may need to have a cardigan on your shoulders. Wish I could be there now.
I have been in late January when it has been hot and sunny. I have also been when it has rained everyday ( from about midday) for 2 weeks and been very windy.
Generally good as others have said, though can vary depending on where you stay - if in the north eg Puerto de la Cruz, expect it to be a tad cooler or cloudier than the sunny south (Las Americas, Adeje, Los Gigantes etc). Have a good time -we've got to wait till March for our visit!
weathert in all the Canaries is generally better in the south of each island - it comes from the north and that's where the precipitation falls. You can see it here
Playa de las Americas is popular, don't go north the weather is usually cooler up there. I think it's the only place where you can get winter sun without spreading out to Australia.
Methyll, I'm not a night club loving druggie who likes being robbed, and I've been to los cristianos 28 times in the last 10 years! We've only been during the winter, when the place tends to have more 'swallows' and have never had a problem. We love it - hands off LC!