Winter has arrived, bringing with it a Monday morning of cold weather records and frost for Sydney.

Lows of 7.3 degrees in the city heralded the coldest May morning in the city since 1999, while Richmond woke to its coldest May morning since 1987 at -1.7 degrees.

Weatherzone meteorologist Rob Sharpe said that Monday would be the coldest morning of the week, thanks to some cold fronts that moved through in the past seven days.

"An air mass moving across NSW dropped temperatures, so we had much colder air in the region," he said.