Port Pirie residents have woken to thick fog in recent days after cold conditions overnight.
The pattern throughout the month of July has seen weak fronts and high pressure systems to follow, which has produced light winds and clearing skies - all good conditions for fog formation.
Bureau of Meteorology senior forecaster Tom Boeck said the combination of clear skies, cold temperatures and moisture cause fog in the region.
"With weak fronts coming through, those systems provide low-level moisture and the clear skies, light winds are all conducive to the formation of fog which has been the case through the Mid North," he said.
"It is a combination of clear skies and that allows the temperature to fall at night and you also need some low-level moisture which gives you enough moisture in the atmosphere for condensation to happen."
At the weekend, overnight wind gusts were recorded about 5kmh to 10kmh, with temperatures reaching as low as 3C on Saturday night into Sunday morning.
Heading into Monday morning, light wind and temperatures as low as 5.1C made good conditions for fog across Port Pirie.
Mr Boeck said residents can expect to more fog and frosty conditions in coming days.
"Through much of this week until Friday, residents can expect cold overnight temperatures with frost patches around," he said.
"For the next few mornings we are forecasting cold conditions with Monday night expected to reach zero degrees.
"Heading into the later part of the week and weekend overnight temperatures won't be as cold with more wind and cloud expected."
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