Sydney looks set to break its record for longest dry spell on Sunday as forecasters predict rain storms will peter out over the Blue Mountains.

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.

The record dry spell is still going. Credit:Peter Rae

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.