So, yes, January is a very early time to see cherry trees start to blossom but what you’re actually seeing are plum trees.
Now both kinds of trees are pretty much the same thing, so no biggee, but plums come out earlier than cherries – global warming doesn’t have anything to do with that.
Oh, here’s what they look like, rather a bit more pink than cherry, in my experience.
Near Clay and Davis, Financial District:
And here’s a nice shot from Flickr: