Former Prime Minister Sir John Key reckons the time is now to build a second harbour bridge in Auckland, amid the ongoing troubles with the current crossing.

Motorists are being warned to stay way from the bridge, with heavy winds buffeting the super city and making for hazardous driving conditions.

NZTA says it may close some lanes of the bridge if wind gusts exceed 80 kilometres per hour, and motorbikes, trucks and tall vehicles should use the Western Ring Route.

As it is, motorists continue to face delays during peak time traffic, with the two middle lanes closed.

Sir John Key told Kerre McIvor there will never be an optimum time to build a second bridge.

"The problem we're dealing with is... [it] take a lot of time, costs a lot of money. But it's a bit like the CBD rail tunnel, we backed that in the end not because we thought it was value for money... but it ultimately unlocked infrastructure opportunities in Auckland.

"Tell me it's ever going to get cheaper... it's not, so you may as well get on with it."

Key adds the reality is, things always take time.