Strong winds forecast in Auckland around lunch time could see lanes on the harbour bridge - or the entire bridge itself - closed for safety reasons.

A strong wind alert was issued by Waka Kotahi NZ Transport Agency at 6.15am, warning motorists using State Highway 1 heading to the bridge to be extra careful this morning.

"Please obey the speed signs. Take extra care, especially if you are in a high-sided vehicle or riding a motorcycle."

Gusts were nearing the 70km/h mark early on - reaching 67km/h at 6.30am. At its peak overnight, gusts got up to around 75km/h.

A passenger on a double-decker bus said she was "nervous" as they went over the bridge - no less because it was travelling on the far-left lane, nearest the ocean.

The NZTA is now telling the public that transport authorities would not hesitate to close lanes or even close the bridge itself for short periods of time, if necessary, for safety precautions.

Motorists are warned that closures can happen at a very short notice.

"Waka Kotahi acknowledges the lane closures will cause disruption and inconvenience this morning," NZTA's Neil Walker said.

"However, safety is our top priority and the lanes closures will be lifted as soon as it is safe to do so."

MetService meteorologist Rob Kerr told the Herald it will be the windiest around lunchtime when gusts are expected to reach 80km/h.

Overnight, however, will be the true test - when gusts will hit 90km/h between midnight and 3am.

That will be the windiest conditions reported on the bridge since a strut was badly damaged when a truck tipped over in freak winds of up to 127km/h just over a week ago, Kerr said.

The damage has been temporarily fixed - but not before Auckland faced several days of traffic chaos around the city; particularly in and around the bridge and via the alternative Western Ring Route.

Traffic heavy this morning

Traffic on State Highway 1 heading into the city, via the bridge, was heavy shortly before 7.30am.

People driving from Silverdale into the city, using the bridge, can expect a drive of about 40 minutes. That trip usually takes under 20 minutes, according to NZTA's website.

The trip from Albany to Manukau, via the bridge, is about a 47-minute drive at this stage.

Anyone driving from Helensville into the city, via the bridge, can expect a journey of about an hour.

Motorway cameras showed congestion was already heavy from SH1 Northcote Rd and Esmonde Rd around 7.30am.

Yesterday, NZTA senior journey manager Neil Walker said more unsettled weather with wind gusts up to 75km/h was forecast for this morning, with winds up to 80km/h on Tuesday.

"The Auckland Harbour Bridge is safe for use despite the damage done to the superstructure last Friday.

"However, it is in a vulnerable state until we complete a permanent repair so we want to do all we can to protect the bridge and the people using it. Safety is our absolute priority."

North Shore residents are once again being urged to travel outside peak hours or to use public transport - either the bus or ferry - to get over the bridge in order to ease congestion on the bridge.

Aucklanders are waking up to showers this morning. Strong westerly winds are also on the forecast, MetService says.

Gusts of up to 48km/h are on the cards too. A high of 16C is expected.

But at 6.30am, the temperature outside was feeling more like "three layers" and one windproof garment kind of weather, MetService said.