Abel Tasman National Park in July

November through April delivers the warmest weather and calmest seas, but also the biggest crowds. December and January see families everywhere, plus higher accommodation prices. March and April hit the sweet spot — still warm enough for swimming but with fewer people on the tracks. Winter hiking works if you don't mind cooler water and shorter days, though some water taxi services reduce their schedules. The weather stays mild year-round thanks to the coastal location, but pack for rain any time. Those westerly storms can dump serious water on the park, turning streams into temporary rivers.