Air quality warnings have been triggered by burn offs in the surrounding areas which have left an acrid haze over the entire city.
ABC Online reports there have been at least 11 days this month where air quality in the Australian city have rated "poor".
The smoke is being caused by the Rural Fire Service conducting "hazard reduction" burnoffs of vegetation around Sydney, but because of the still conditions the smoke has been lingering.
A webcam image of Sydney Harbour taken about 9.45am local time on May 29 2018.
According to the Office of Environment and Heritage air monitoring, current particle levels in Sydney are "unhealthy for sensitive people, and could cause symptoms, especially in people with heart or lung disease".
Webcams and photos taken today show very poor visibility, and satellite images show that smoke haze is settling in nearby valleys, as well as the Sydney basin itself.
A satellite image of the Sydney region, taken May 27 2018, shows smoky haze in the Sydney Basin and nearby valleys.
Source: NASA Worldview