Summer: air 30+°C, winter average around 15°C. Water: 5mm needed in winter, no wetsuit needed in summer. Beginning of November required 4mm wetsuit, due in part to wind coming from N (cold).
In NW winds sideshore and gusty. Gusty in the sense that for around 10 minutes it may be 6 Bft, then the next 10 minutes might drop back to 5 Bft, and so on. Not gusty in the sense of off/on power while sailing.
From Barcelona, take expressway (tolls! 5 of them! 15 Euro). From Barcelona, 1.5 hours, south to Tarragona. Then further south to Amposta and here east into the delta to Riumar.