Wellington Airport says fog has caused several flight cancellations on Friday evening.MetService said a southerly wind had pushed a low cloud shelf into Wellington over the past few hours on Friday evening.Passengers are being advised to check directly with their airline for the latest information before travelling to the airport.Meteorologists earlier said as temperatures cool in the evening, a thick bank of mist could sink to surface levels.The cloud bank was expected to last through the afternoon to the early hours of Saturday morning.Meteorologist Alwyn Bakker earlier said the southern coast of Wellington would be most exposed - including the harbour and airport."So you get that sea fog when sea surface temperatures and air temperatures are very close together."So with a southerly the air is cooled down, the sea takes a little bit longer to cool down water - it hangs on to heat better than air essentially."He said low visibility might impact flights, depending on how much moisture builds in the air."Basically, planes like to see the ground before they land."Auckland Airport affected by fog on Friday morningFog restrictions were in place at Auckland Airport this morning.By 7.20am, several domestic regional flights had been cancelled as well as some arrivals.A number departing had been delayed as well as arriving.Of the main trunk domestic flights, one to Christchurch had been delayed, as had an arrival from Dunedin.International flights were not affected by the fog.