MetService earlier confirmed the city had experienced 29 days of rain. It's the second record in a row, after there were 28 days of rain in July.
Clark said Auckland is due to get another belt of rain and as that low inches closer could see several bands of rain lashing the city.
"[Auckland] could possibly be under a heavy rain watch or warning for tomorrow so that's something for people to keep an eye out with those strong northeasterly winds."
She said there was a lasting ridge over the country today, as the low develops out to the northwest of the country.
"So ahead of that front these northeasterlies are bringing in moist, warm subtropical air, so that's rain-laden. With that low there will be belts of quite wet weather, especially the upper North Island, and that band of rain will move further south, affecting the eastern coast.
"There will be strong northeasterly winds with it too."
She said the system coming through was "complex", with several bands of rain landing at different times affecting different areas.
The low was likely to hit the country around Wednesday or Thursday, bringing with it cooler southerly temperatures.
"As that low moves across we are expecting some southerlies, so that will be affecting the east coast as well. They're not really cold ones. As that low moves across it's dragging in moist air on the eastern side of it, so it's not a straight southerly from Antarctica coming from those really cold waters.
"Temperatures will drop as we head into the latter part of the week, especially the east coast of the South Island, but they're not anything really significant in terms of huge temperature changes."
Overnight temperatures will remain warm prior to the low landing, with Rotorua and Whakatāne likely to get 12 or 13. But as it turns southwest it would return to "more average September" temperatures.
"Everyone is going to get a little bit different at different times. Everywhere will get a bit of rain but it's brief for some areas."
Clark said heavy rain and wind watches and warnings will be issued by MetService later this morning.
While the eastern coast will bear the brunt, Taranaki and Whanganui would also experience some heavy rain.