I'd say the canary islands are probably the warmest in Europe in January, but it won't be hot, probably low to mid 20s I think.
Canary Islands should be around 22 degrees then. Tenerife is best weather wise then. But I personally prefer gran canaria for the food, atmosphere and hotel choices. Still decent weather around 21 or 22 but can be windy
Not in Europe but you’d have nice weather in egypt at Sharm El Sheikh or Hurghada for a beach vacation in January