Auckland is under a state of emergency.

Building assessors have now red-stickered 102 Auckland houses as Auckland Transport says motorists should consider travel today in the face of widespread red and orange weather warnings.

In its latest update Auckland, Emergency Management says there are also 375 yellow-stickered properties, which means there is moderate damage and access is restricted while 857 are white-stickered which means no limits on access.

The city north of Orewa is on a red alert for heavy rain from 5pm today until 8am Wednesday while the rest of the city is under an orange warning.

Auckland Transport's Andrew Allen says school closures mean less pressure on roads and that is welcome.

He says the harbour bridge may be closed or have restrictions later if forecast high winds arrive.

Far North Mayor Moko Tepania says Civil Defence Northland is prepared for managing evacuations in the region if they are needed.

The National Emergency Management Agency is warning that the severe weather may cause flooding, slips and damage.

Tepania says the region has experience with storms but advises Northlanders to be prepared to evacuate if it is required.

He says evacuation centres are ready to open if needed.

Red heavy rain warnings (the highest-level warnings) are in place for Northland, Auckland north of Orewa and the Coromandel Peninsula.

In the north of Auckland up to 120mm of rain over 15 hours is expected, with up to 80mm everywhere else.

While that's nowhere near the record-breaking amounts that pounded the city last week, emergency officials say the ground is so saturated even ordinary rainfall will cause slips and more flooding.