Weekend washout: Think twice about celebrating Mother's Day outdoors in upper North Island with a deluge of rain on the cards

A messy low will bring rain to much of the country over the weekend, the worst of it hitting just in time for Mother's Day on Sunday.

TVNZ meteorologist Dan Corbett says the low will receive some energy from the tropics, as well as from a huge low affecting Victoria, Australia right now.

Ahead of this low from the tropics, a separate low is set to move into the West Coast of the South Island tomorrow and slowly spread north, with rain reaching Auckland by the evening.

MetService has issued a heavy rain warning for Westland tomorrow, with the possibility of 100mm of rain hitting the region between 8am and 11pm.

Saturday and Sunday is when the low from the tropics moves in to put a dampener on Mother's Day celebrations.

The weather system is expected to bring a deluge of rain, mainly to the upper North Island from Taranaki to Northland, on Sunday.

Most of the South Island will also receive rain for Mother's Day, with Invercargill looking like the best place to be if you want to stay dry.