MetService has warned Aucklanders to be wary of isolated downpours over the next two days.
The forecaster says it's the first time the region has seen an elevated risk of downpours since 2017.
Heavy rain is classified by MetService as being 6mm an hour, while downpours can consist of 25mm an hour.
"While there is decent potential for downpours tomorrow, high-impact rainfall tends to be highly localised," MetService said on Twitter.
"While rain will be setting in around the North Island throughout today, the heaviest falls are expected from later this evening and through Wednesday.
"Rain on the way for the Deep South from Thursday."
Vector is also warning Aucklanders to prepare for the possibility of power cuts due to the wild weather.
“We are asking Aucklanders to do their best to prepare by following the checklist below and ensuring their devices and power banks are fully charged today, particularly those students preparing for their end of year exams," Vector’s Head of Network Field Services, Marko Simunac says.
VECTOR'S STEPS YOU CAN TAKE TO BE PREPARED
• Always stay away from fallen power lines or damaged electrical equipment.
• Watch out for falling tree branches as these can cause damage to power lines.
• Avoid possible damage to electrical appliances (in the unlikely event there is a power surge when the power is restored) by switching off appliances at the wall.
• Keep a torch and spare batteries handy and ensure that you have at least one telephone that does not rely on electricity for operation.
• If you have one, ensure your electric vehicle is charged.
• Ensure that an alternate fuel is always available for cooking (e.g. gas for BBQ).
• Tie down objects on your property that may be impacted by strong winds (ie: trampolines, BBQs and BBQ covers).
• If you are on tank water please ensure you have plenty of bottled water available.
• If life or property is at risk, call 111.
• We ask the public to not approach our teams for their safety and that of our crews.