I fed some last month when the temperatures were in the 60s. I fed really thick stuff as well. I also put dry sugar on the top, in the mountain camp style.
My big hive is still heavy as all get out, but my 2 little one (from a late split) are light and they've eaten all of the sugar from the top. I am trying to decide what is best to do as well with February and March ahead. I will definitely be putting dry sugar on top again. Not sure about the syrup. I've always read that spring feeding should be 1:1 to encourage brood building, but not sure if that is what we want to be doing now.
Hopefully, someone with more experience will advise. It sure has been a weird winter, my bees have been flying almost constantly. I'm not sure they ever really clustered.