A rapidly deepening low will bring gales and heavy rain to much of New Zealand, forecasters warn.

MetService has issued severe weather warnings for the northern and central North Island and the northern South Island as well as Otago and Fiordland for Sunday and Monday.

People are being warned to look out for rapidly rising waterways, surface flooding and slips in the affected areas.

Heavy rain is forecast for the eastern ranges of Waikato, Bay of Plenty and western Nelson on Sunday evening and Monday morning.

A southeast flow between the deep low and a ridge to the south of the country is expected to bring heavy rain to eastern Otago and southern Fiordland, with severe gales gusting up to 130km/h forecast in exposed parts.