MetService Meteorologist Sarah Haddon said the fog was expected to "get rained out pretty quickly" by showers over the city this morning.
Aucklanders should expect to hear fog horns this morning as both harbours are enveloped in thick fog.
Coastguard duty officer Melissa Ousey said once ferries and ships started going, the horns will start too.
The fog is set to clear well in time for tonight's All Blacks and Lions decider at Eden Park.
Conditions are expected to be calm at the game, with the odd shower but not enough to dampen the spirit.
DEVELOPING NEWS – ISSUED 7:20am
SIGNIFICANT SNOW EVENT ON TRACK FOR MIDDLE STAGES OF NEXT WEEK - SNOW TO NEAR SEA LEVEL...
Posted by Canterbury Weather Updates on Friday, 7 July 2017
It was a cold night in the South Island with a low of -10C recorded at Lake Tekapo.
Police have issued a warning to drivers in the Southern district not to go out on the roads at the moment due to icy conditions.
"If you don't have to go out anywhere today - please stay in until it's safe to head out and check weather forecasts before making tracks.
"You often won't realise you are heading towards black-ice before you hit it, making it potentially lethal to drive on the roads at the moment.
"It's not even wise to go out walking or cycling as the footpaths will be affected too."
Police said it's been raining again overnight, making driving in the icy conditions more dangerous than usual.
Police have received numerous reports of crashes in Central Otago, Southland and Te Anau areas this morning, due to icy conditions.
According to reports, there is black ice on State Highways 6, 8, 94 and 97.
Police also attended crashes in Southland and Clutha last night, where drivers slid on black ice and lost control.
"We've also received a number of reports of near-misses due to the black ice on roads across Southland and Central Otago," said Senior Sergeant Jared Kirk.
"Tonight and over the weekend, we are expecting very low temperatures.
"Particularly where the roads get no sun, motorists can expect black ice on our roads day and night."
Police ask that all motorists slow down, take extra care on bends and corners, and to buckle up at all times.
UPDATE 6.50PM - JUL 8 - STATE HIGHWAYS - WARNINGS & CLOSURES
• SH94 Te Anau to Milford - Ice - Towing Restrictions...
Posted by Waka Kotahi NZ Transport Agency - South Island on Friday, 7 July 2017
MetService has issued road snowfall warnings for Arthur's Pass and Milford Rd.
From 8am to 2pm, up to three centimetres of snow was expected to settle on Arthur's Pass, above 700 metres.
Icy conditions were also likely, even below 700m.
Snow showers may affect Milford Rd for a time this morning.
Passengers should check Auckland Airport's website www.aucklandairport.co.nz or the Auckland Airport app for the latest flight arrival and departure information.
