“Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.
“Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.”
A heavy rain watch is also in place for the ranges of the Eastern Bay of Plenty between 8pm Monday and 8am Tuesday.
Rain to interrupt New Zealand’s hot weather this week
MetService forecaster Tuporo Marsters said Kiwis best take advantage of any sunny weather they can get before the rain sets in this week.
“If you haven’t washed your car, now’s a great time to get that much-needed car wash and watering done,” he said.
“Frontal rain for much of the motu with heavy falls about Taranaki Maunga and downpours from east Northland to the Bay of Plenty in the evening.”
There will be cloudy conditions passing over the North Island in the coming days - with rain from Taranaki to Wellington.
The capital can expect scattered showers with strong winds in the afternoon today and a high of 21C.
Both Tauranga and Hamilton can expect a high of 25C today with showers turning to heavy rain in the afternoon.
Gisborne stays dry until the rain arrives in the afternoon. Northerly winds will ease in the afternoon amid a high of 27C.
There are also heat alerts today in Whangārei, Auckland, Whitianga, Thames, Napier, Whanganui, and Motueka.
A cold front will be moving up the South Island, bringing heavy rain to the West Coast and triggering a rain watch for the Westland ranges until 8pm today.
Then, as the week approaches, it will be mainly fine with a few showers in the south.