It might feel like the current dry conditions will never end but the second half of summer could be wetter and windier than usual in the north thanks to warm seas and the La Niña weather system.

The latest forecast from the US National Oceanic and Atmospheric Administration suggests a large swathe of New Zealand will see high-than-average rainfall from January - March.

Niwa has also predicted more rain than normal for Auckland and Northland in its seasonal climate outlook for December-February.

While summer temperatures will be hotter than normal everywhere, tropical lows are likely to bring storms with deluges and even the risk of ex-tropical cyclones for northern New Zealand later in the summer.

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The south and southeast of the country are forecast to experience higher pressure than normal, with a high chance of drier-than-normal weather.

Apart from the north of the North Island, rainfall is likely to be around average across the summer, except in the east and west of the South Island where Niwa is expecting less rain than normal.

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The La Niña conditions that started making themselves felt in November are likely continue through till February, according to Niwa. The weather pattern typically brings hotter than normal temperatures along with high humidity.

Weatherwatch has also predicted more rain for the second half of December although it's "hit and miss", with inland, western and northern areas most likely to remain dry.

Coastal waters remain warmer than average around New Zealand, especially off the coast of the South Island, which is likely to ramp up the heat throughout summer but also increase rainfall levels.

Sea temperatures are 1-3C warmer than usual around the country, according to the MetService.