The answer to your question depends upon the flexibility of your definition of 'Europe'. The Canaries lie off the coast off Africa but are often regarded as a 'European' destination by travel operators. Average daily maximum temperatures, in January and February, are around 21C (falling to about 15C overnight):
http://uk.weather.com/weather/climatology/SPXX 0210
Some ABers suggest Cyprus as a winter destination. Once again, it's stretching the definition of 'Europe'. (Cyprus is an EU member state and is regarded as a 'European' destination by travel operators but, geographically, it's in Asia). However, maximum daily temperatures will only be around 14C or 15C. (6C overnight):
http://uk.weather.com/weather/climatology/CYXX 0004
Within 'true' Europe, you need to be as far south as possible. However, temperatures in southern Spain and Portugal will only be fairly similar to those in Cyprus:
http://uk.weather.com/weather/climatology/POXX 0016
Southern Italy and Sicily also offer similar conditions:
http://uk.weather.com/weather/climatology/ITXX 0055
It's much the same in Malta:
http://uk.weather.com/weather/climatology/MTXX 0001
and in the Greek islands:
http://uk.weather.com/weather/climatology/GRXX 0017
So (as long as you don't mind stretching your definition of 'Europe')