Sydney's residential property boom has delivered a record month of stamp duty receipts for the NSW government as the market prepares for what is expected to be the busiest auction weekend in history.

The surge in property sales may also hand a political windfall to the O'Farrell government, which is poised to reveal a stronger than anticipated financial position before the 2015 election.

Still strong: Sydney property market will host 757 auctions this weekend. Credit:Tamara Dean

Data published by the Office of State Revenue reveal $356.8 million in stamp duty poured into government coffers from residential property sales last month - the highest monthly figure since 2005-06 when records began.