Major flooding is now occurring at North Richmond and Windsor, however rain seems to be easing around the Hawkesbury-Nepean catchment, and officials are hopeful that the worst is behind us.
NSW SES Hawkesbury Unit Commander, Kevin Jones, said: "We're seeing a drop in the river slightly at North Richmond, so it seems to have peaked. We're still getting a small rise - very slow rise - at Windsor, it's close to getting to its peak, in the next few hours we should see it flatten out."
Mr Jones warned, however, that the situation could change rapidly, as the Bureau of Meteorology (BOM) was constantly updating its advice.
Numerous areas around the Hawkesbury River were evacuated over the weekend, in what has been the fourth flood emergency in the Hawkesbury in two years.
The Hawkesbury River at North Richmond peaked at 14.18 metres around 3.15am Monday, with major flooding. The river was at 13.96 metres and falling at 10.10am Monday.
The BOM predicted that the Hawkesbury River at Windsor may reach around 13.30 metres Monday afternoon, with major flooding. The river was at 12.56 metres and rising at 9.45am Monday.
The Hawkesbury River at Sackville may reach the major flood level (9.70 metres) Tuesday morning, according to the BOM.
The Hawkesbury River at Lower Portland may reach the major flood level (7.60 metres) Monday afternoon, and at Wisemans Ferry it may reach the major flood level (4.20 metres) during Tuesday, the BOM stated.
Parts of Ebenezer, Sackville, Sackville North, Cumberland Reach, Lower Portland, Leetsvale, northern Windsor, Oakville, Pitt Town South, Cornwallis, and low-lying areas of Richmond Lowlands, Freemans Reach, were among the areas that received evacuation orders over the weekend.
Numerous suburbs were put on evacuation notice, including McGraths Hill.
Mr Jones said Australian Defence Force workers and local SES volunteers door-knocked on McGraths Hill homes on Sunday night to warn residents that they might be evacuated during the night, however evacuation orders have - as yet - not eventuated.
Mr Jones said residents - thought showing 'flood fatigue' - were on the whole better versed about what to do this time around.
"I can't imagine what it's like having to move out for the fourth time [in two years], but everyone seems to be more practised and prepared," he said.
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"We haven't had as many requests to help people get out of places, and we haven't had as many grumbles that we didn't tell them early enough. They're pretty savvy, the locals that are directly affected by it."
Mr Jones said the team at the local SES hadn't had any "major issues" with residents doing the wrong thing this time around. However, he reminded people that they should never drive through flood water.
"We had a few people driving into flood water again - which is a bit disturbing - but something people do silly things in the heat of the moment," he said.
"We performed six or seven flood rescues yesterday (Sunday) when people drove into the water, and a couple of livestock stuck on an island, and we haven't had any flood rescues so far today (Monday).
Local Hawkesbury SES volunteers rescued a mother and her six-week-old baby from Gronos Point over the weekend.
"We had a team there delivering a door-knock for an evacuation warning and the lady, who was pretty new to the area, got a bit caught our and we asked our boys and girls to give her a lift back to the other side, which they did. She wanted to remove herself from the problem and the roads were already cut - the water came up fairly quickly," Mr Jones said.
A severe weather warning is still in place for the Hawkesbury.
The East Coast Low that was looming Sunday night has weakened into a trough over the Hunter district, however onshore flow south of the trough is still directing humid air onshore, causing moderate to at-times heavy rainfall in areas near and to the south of the trough, the BOM stated.
Drier air will push gradually northwards up the NSW coast through Monday afternoon, clearing most of the rain out of the Illawarra, Blue Mountains and Sydney regions by late this evening.
Although rain rates have generally eased, heavy rain which may lead to flash flooding is still possible today in the Illawarra, Blue Mountains, Sydney Metropolitan, and parts of Hunter (including Central Coast) districts.