Fog has been blanketing parts of southeastern Australia this morning, including the Adelaide and Canberra areas, affecting road and air traffic. A road weather alert has been issued for Adelaide. Visibility has been reduced to only 100 metres at Adelaide and Canberra airports, potentially delaying flights and challenging those on the road. Visibility is likely to stay fairly low until about 9am until the wind picks up and disperses it. Recent rain has increased the humidity over southern Australia and now a high pressure system has caused wind to become light, enabling the moisture to condense and form fog. Fog has been fairly thick in patches elsewhere in South Australia, the ACT, Victoria and New South Wales this morning. Visibility has been as low as 100 metres in western Sydney, Albury, Armidale, Wagga Wagga, Griffith and Ballarat. Looking ahead, fog is likely to redevelop across a similar area on Monday morning thanks to the slow-moving high pressure system keeping wind light.