A large cold front comes in off the Tasman Sea today, bringing significantly heavy rain to the west of the South Island and more warm to hot North-Westerlies to the East Coast. Mainly fine across the North Island with some late rain developing as the front moves up the country, but this front weakens as it heads north.

In a welcome change for many in the north, it’s not the Auckland region at the centre of a heavy rain forecast, but rather the West Coast of the South Island for Waitangi Sunday. Heavy rain and strong, gusty Northerlies are expected to develop across the region from early morning, with a daily accumulation of 250-350mm in the ranges, and up to 150mm near the coast. A similar story for the Buller and Tasman districts, with rain setting in and becoming heavy for a time later in the afternoon. 80-150mm accumulations are likely by the end of the day.

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The warm streak continues in the East and South of the South Island, however thick high cloud is expected to increase, and possibly result in some ‘spillover’ showers at times from late morning. A period of more persistent rain will spread eastwards across Marlborough later in the day. Breezy Northerlies in the South, but strong and gusty Nor’Westers about inland Canterbury and Marlborough- rising to gale in exposed places. Strong, gusty North-Easterlies along the coast. Expect mild temperature highs again, in the mid to high 20s.

Now to the comparatively ‘laid back’ North Island, a mainly fine day with increasing cloud and breezy northerlies should be the gist of the day for most, except for some isolated showers about the Bay of Plenty and the Central Plateau. Northerlies strengthening in the south and west during the afternoon, possibly rising to gale about Wellington, Manawatu and Taranaki. Rain is likely to develop and spread eastwards across the island from evening with the arrival of the front, potentially heavy for a time for western districts. Our familiar warm and humid airflow continues, with temperature highs ranging across the mid 20s for most.

• By Jono Hartland
• WeatherWatch.co.nz