Byron Bay's subtropical climate means there is never a bad season, but there are better and worse times to visit. Autumn (March–May) is the sweet spot: water still warm from summer, crowds thinning out, and temperatures in the mid-20s. Spring (September–November) is similar — warm enough for the beach, not yet peak season. These are the times to come if you want space.
Summer (December–February) is peak season. School holidays bring enormous crowds to the town, accommodation prices spike, and the streets become genuinely difficult. The weather is hot (often 28–32°C) and humid, with occasional afternoon storms. Worth avoiding unless you book months ahead.
Winter (June–August) is mild by any Australian standards — daytime temperatures of 18–22°C are typical, and the sea drops to around 19°C. It is quieter and cheaper, and this is prime whale-watching season: humpback whales pass offshore during their northward migration from June through November, with the peak in July and August.
Byron Bay Bluesfest is held every Easter long weekend at a farm north of town. It is one of the best music festivals in Australia and draws large crowds; book accommodation well in advance if visiting at Easter.