It certainly didn’t feel like the second week of May in Sydney on Friday, as the mercury climbed nine degrees above average to a summer-like high of 28.5 degrees.

A stream of warm northwesterly winds that developed ahead of an approaching front caused Friday’s burst of late-autumn warmth in Sydney.

Image: Forecast surface temperature and wind on Friday afternoon, showing northwesterly winds transporting warm air over the Sydney Basin.

The city’s top of 28.5 degrees was its highest temperature this late in autumn since 2012. Impressively, it was also just the fourth time on record that Sydney has been this warm, this late in the season, with data going back to 1859.

Sydney is forecast to dip to a relatively warm 16 degrees overnight and reach the mid-twenties on Saturday as warm air lingers over the city. A cool change will arrive on Saturday night, dropping the city’s maximum temperature back to about 19 degrees on Sunday.

• Written by Ben Domensino, Weatherzone.com.au