The Bureau of Meteorology has forecast a 50 per cent chance of a shower or two but even if they occur the city's gardens cannot hope for much of a drink, with less than 1 millimetre of rain expected.

Sydney and NSW recorded their driest Septembers on record, receiving one-seventh of the average rainfall. And on Saturday, Sydney matched its record for the greatest number of consecutive days receiving less than 2mm of rain, equalling a 64-day stretch from August to October in 1989.

The last rain that fell on the city was 0.2mm on September 14 and before that 1.2mm in late August.

"It's not looking hugely promising," the Bureau of Meteorology's Gabrielle Woodhouse said of Sydney's rain outlook. The meteorologist said thunderstorms in the state's west were not likely to bring more than "a couple of drops" past the foothills of the Blue Mountains.

"We really haven't had any rainfall effectively from early August."

While the bureau forecasts a series of possible showers on Monday, Thursday and Friday, only next Saturday's expected rainfall band extends above 2mm (1 to 4mm).

Sydney on Sunday faced a maximum temperature of 23 degrees, with light winds becoming northerly in the afternoon. Possible showers were not expected until late afternoon or the early evening. On Monday, the temperature is set to hit 30 degrees, with a 50 per cent chance of afternoon showers and the possibility of a midday thunderstorm.

Senior Weatherzone meteorologist Jacobus Cronje, who predicted Sydney may see 1 to 3mm of rain on Sunday, said high pressure systems over Australia's interior had blocked many moisture-laden cold fronts.

"Up until the middle of the month, we are going to see the odd shower, nothing significant," Mr Cronje said.

But NSW in October is set to receive average or slightly above average rainfall, meaning a wet 10 to 15 day period in the second half of the month.