Common House Martins? January?

It´s January still, winter in my books, but there are cherry and almond trees in blossom. We still get a bit of frost, hailstone and they are salting the roads every now and again. Oh look a House Martin. Eh? What are these guys doing here so soon? About 20 were flying over the house we were staying in. Thankfully I grabbed my camera since nobody in the house would believe me that I saw some of these. Everywhere I read it says they come back in April or so with the swallows. Impossible to be here now they said. Oh well, here´s the proof. Common House Martins seen in Estremadura in January.