Unseasonably humid conditions are being blamed for heavy patches of fog over most of the Top End.
Weather bureau forecaster Chris Davies says the fog extends all the way down to Borroloola and Elliott and the high humidity may hang around until Sunday.
Visibility at Darwin International Airport was down to 200 metres and the early morning humidity level there was more than 97 per cent.
One flight from Adelaide was delayed but others are not expected to be affected.
Mr Davies said the fog was expected to burn off quickly in the morning sun in most coastal areas of the Northern Territory.
"We might end up with some low cloud hanging around," he said.
"The stuff that will hang around the longest will probably be some sea fog in the Southern Gulf."
© ABC 2012
14:38 EST The NSW Government has been asked to consider additional measures to help farmers cope with dry conditions in the future.