Parts of the upper north island have awoken to fog again this morning

It's the third day parts of Auckland have experienced fog -- and it's causing domestic flight cancellations and delays.

Auckland Transport's warned ferries may be cancelled.

Areas of Northland and Waikato are also foggy.

MetService meteorologist Mmathapelo Makgabutlane says it's the time of year that fog is expected.

She says people driving should take care on the roads because the fog is quite widespread.

Makgabutlane says foggy mornings have also been a feature for the South Island this past week.