Rizhao's appeal is heavily seasonal. June through September is the beach season, with sea temperatures warm enough for swimming from mid-June. July and August are peak domestic holiday months and the beaches get genuinely crowded; late June and September are better choices for those who prefer space. The water quality and weather in September is often excellent.
Spring (April–May) and autumn (October) offer mild temperatures and good conditions for inland hiking at Wulian Mountain. Winter is quiet and cold — the beaches are empty and the city functions as a normal small Chinese city rather than a resort, which has its own appeal if you're using Rizhao as a base for exploring the coast.