The best time to visit Vinaròs is spring or early autumn. March to June is ideal: the weather is mild, the gamba roja season is in full swing (running from roughly March through November), and the town is not yet crowded. September and October are similarly good.
July and August bring Spanish domestic tourists and heat — temperatures along this coast can reach 38–40°C, and the beaches and restaurants get busy. The Carnival in January–February (dates vary with the calendar) is one of the livelier events in northern Valencia and worth planning around if you enjoy proper Spanish carnivals. Winters are mild by northern European standards — around 12–15°C — and the town is quiet and fully local.