Auckland's Mangatangi Dam in the Hunua Ranges. Photo: Supplied / Watercare
Auckland's water agency will ask residents to conserve water, with the dry summer likely to last into the autumn.
The summer forecast is for more northwesterly winds than normal throughout the country, and dry weather in the east.
Watercare head of production Peter Rogers said the region's dams were at good levels.
"We are planning to manage the dam supplies. We'll be looking at the weather forecast as it tracks along, looking at our dam storage levels which are currently in a good position and we'll also be tracking the demand through summer."
At the end of 2023, the region's dams were 93 percent full.
Watercare would also draw water from the Waikato River - it can take 300 million litres of water a day from the river year-round.
"We will actually supplement our supply and manage the supply from the Waikato River to ensure we have plenty of water to take us through this summer."
Auckland residents use an average 423 million litres per day, but this can spike by 100 million litres on a hot day.
The highest demand for water was in February 2020, when it jumped to 568 million litres per day.
"We will see our peak coming around February, that's typically when people come back from holiday into Auckland's nice dry weather which is the summer we've all been looking out for. That's when we'll be seeing the pressure."
Rogers said it was still important to conserve water, such as limiting the use of sprinklers and showers to four minutes.
"We won't run out but definitely we would ask people to be careful with water. We don't want the very large increases in demand.
"While we are in a good position now, the issue is not going to be this coming summer, but… if we don't get the recharge over the winter or if we have two back-to-back summers that are very hot and dry, that's when we get pressure on our treatment plants and networks."
He said any spikes in water use would pressure on supply.
"We're always asking people to be very careful with water."
Halfway through 2023, NIWA's data showed Auckland had already recorded more than a year's worth of rain.