A front which has lashed western areas of the South Island with up to 50mm of rain is set to peter out as it heads north - and Auckland is expected to get 70 per cent less rain than average.
Water levels are down 20 per cent for this time of year, and despite the region getting healthy rainfall last week, the next week isn't looking good.
In total, dam storage levels are at 65.8 per cent, compared to 86.71 per cent normally for this time of year.
Aucklanders appear to be doing well with their water consumption. Watercare's figures today show the region used 424 million litres and had a seven-day rolling average of 437 million litres.
The target for January is 461 million litres or less a day for the rolling seven-day average.
In the past seven days, Auckland received little rain, while the week prior the rainfall was 31 per cent more than usual, but that's coming off the back of two earlier dry weeks, 43 and 57 per cent less than usual, respectively.
Watercare is now expecting this week to be worse, with 70 per cent less rain than usual.
"We do need to keep up the good work and continue to be mindful of our water use," a spokeswoman said.
"It has been a dry start to summer – December had less than half the normal rainfall. This past week we didn't get a drop of rain in our water catchments.
"Previous forecasts had indicated a wetter-than-normal summer, but this has not yet panned out."
Since restrictions were introduced in May, Aucklanders had saved an estimated 8 billion litres, "which was an outstanding effort, particularly given Aucklanders are already the most efficient water users in the country".
Auckland is currently in level one water restrictions, so people can use a hose as long as it is handheld and has a trigger nozzle.
"Sprinklers are not allowed. And inside, please keep your showers short – four minutes or less. If you need to have two showers a day, make them two minutes each."
A small paddling pool is recommended if children want to cool down, then the water can be reused in the garden afterwards.
Watercare said it was also working to bring online new water services.
"The new Papakura Water Treatment Plant, which treats water from Hays Creek Dam, will go into service later this month, providing up to 6 million litres a day. We are also building a new water treatment plant next to our existing Waikato Water Treatment Plant, which will provide up to 50MLD this winter."
MetService meteorologist Peter Little said through to midday Wednesday, the area would get about 5mm to 10mm of rain, some areas less and some up to 20mm.
"So it's not looking like it's going to be a big drop in the lakes. It will be helpful and give people's gardens a bit of a watering, though."
It will help today's Prada Cup racing, though as winds are set to pick up this afternoon: the forecast is for 15 knot northwest winds, increasing to 20 knot northerlies.
Around the country, Taranaki and the Tararua Ranges are likely to get a bit more rain, but eastern areas will remain dry.
A southwest change kicks in on Wednesday into Thursday when temperatures will drop up to 10C in the South Island.
Dunedin will drop from 25C today to 15C.
Little said the temperature change wouldn't be as dramatic in the North Island, but people would definitely feel the impact of the southwester.
Auckland will drop from 27C today to 21C, and 20C on Thursday.
Until then, the hot weather will continue. Whangārei and Gisborne can expect 30C, Auckland and Tauranga 27C and Hamilton 26C.
In the South Island today, Kaikoura is the hot spot with 28C. Christchurch and Ashburton are set for 27C.
The front is currently expending all its energy in the South Island, while central New Zealand - Wellington, Wairarapa - are bearing the brunt of the strong winds with severe weather warnings issued.
The wind has already picked up around the country and that will also continue.