Generally, the beach season in Mallorca runs from May to October. Best DWS conditions start in late September when the temperatures drop slightly and the sun stays lower so that it dries deep holds and tufas. Earlier in the season it might be extremely hot. Well, the hot summer conditions are good for beginner climbers who spend more of their time in the water. October is probably the best time for pro DWS guys. You can also read about some tips on Up That Rock.