A low pressure trough and an offshore low are directing showers and cool air over much of south-eastern Australia and will probably deliver Sydney's coldest November weekend in 11 years, Tom Hough, a meteorologist with Weatherzone, said.

The mercury struggled to break above 17 degrees for Sydney, and across the basin, throughout Saturday. That's shy of the 19-degree maximum forecast by the Bureau of Meteorology, which also tipped about 1-3 millimetres of rain.

Sunday is looking just as miserable as Saturday, with a temperature range of just 15-19 degrees across the 24 hours. Another 3-6 mm of rain is expected.

However, strengthening winds and more rain will make Monday potentially bleaker still, even if temperatures do start to warm up a bit to a top of 24 degrees.

For now 25-40 mm of rain is forecast for Monday, with winds possibly reaching 70-90 km/h along the coast, late in the day, Mr Hough said. There is also the chance of an afternoon or evening thunderstorm.

Warmth on the way

Much of next week will also be on the cool side, with day and night temperatures a couple of degrees below average for most days.

Sydneysiders are likely to have to wait until late next weekend and early the following week for temperatures to warm significantly above normal for November.

The burst of chilly weather follows another relatively warm October. Sydney posted its second-warmest average minimum temperatures for the month, trailing only October 2015, with night 2.4 degrees above average.

Farmers and gardens have reason to welcome the continuing spell of rain. Over the next eight days, the NSW coast will be among the wettest patch of Australia, the bureau said. (See chart below.)

While rainfall has picked up in the past couple of weeks, it will take a while to claw back the deficit after a record 65 consecutive days in Sydney with 2mm or less that ran from August into October.

Even with the better falls towards the end of the month, Sydney's October rainfall tally of 62.8 mm was less than a third of the evaporation levels. The latter reached 197.6 mm for the month, according to the bureau.

At the end of October, the five-month rainfall deficit map of Australia has a large area of NSW among the regions showing unusually dry conditions.

(See bureau chart below, show serious rainfall deficiency (pink), reaching worst on record (red).)

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