Playa de la Malvarrosa (Valencia) is a hot place!! Temperature wise ! So you could easily play during winter with the right cloth. However during spring and summer, afternoons can be very hot. And you often need to stop playing during a few hours.
Playa de la Malvarrosa (Valencia) sand is perfect for beach volley, deep enough for diving without hurting yourself. Playa de la Malvarrosa was named after mallow roses, a type of flower that used to grow on the beach. Sea water is not the nicest around here but sufficient for a quick dive.
Not as easy as Barcelona but close! There are multiple meetup/facebook groups, class for beach volley in Valencia. Head to BeachBol, a beach bar at the start of Malvarrosa Beach for beach volleyball matches.
The beach is very wide and long, so normally enough spaces for beach volley net. However it sometimes can be, especially during spring and summer be difficult to find a spot for your net.