The Kapiti Coast is noticeably drier and sunnier than Wellington, sheltered from the worst of the southerlies by the Tararua Range. Raumati is pleasant most of the year, but the seasons make a real difference.
Summer (December to February) is the obvious peak. Long days, warm water, and school holidays bring Wellingtonians up in numbers. The beach is busy on weekends. Kapiti Island permits sell out quickly — book December visits well before November. Average highs around 22–24°C.
Autumn (March to May) is perhaps the best time. Crowds thin after Easter, the sea is still warm from summer, and the light over Kapiti Island in the late afternoons is exceptional. Fewer weather systems come through.
Winter (June to August) is quiet. The village is genuinely sleepy. Water temperatures drop to around 12°C, which discourages swimming but not beach walking. Southerly storms can be dramatic — good for watching surf break against the island. If you want solitude, winter delivers it.
Spring (September to November) can be unsettled, with fronts coming through regularly. But the days lengthen quickly and Kapiti Island is in full voice — kaka breeding season means the noise level from the forest is remarkable.