Government forecaster, MetService, has tonight issued rain warnings for the upper North Island.

The warnings, issued at 8:46pm Friday, are for the ranges of Gisborne north of Tolaga Bay and the Coromandel Peninsula.

They warn that rain is expected to become heavy Saturday evening, and from 9pm Saturday to midday Sunday 80-140mm could accumulate.

Maximum rainfall intensities of 20-25mm/hr are possible. Note: Further significant heavy rain is likely to accumulate after midday Sunday and into Monday.

WeatherWatch.co.nz will bring you full details on this developing sub-tropical low on Saturday morning with extra updates across the weekend,.