Sydney may have just had its coldest day since 1984 and its coldest August day since 1962.

A thick blanket of clouds, persistent rain and a cold air mass saw temperatures struggling to reach double digits across much of the Sydney Basin on Tuesday.

Image: Composite satellite and radar over Sydney at 3pm AEST on Tuesday.

Sydney's main weather station at Observatory Hill, located next to the Harbour Bridge, had only reached a post-9am maximum temperature of 10.2ºC by 5pm, based on the day’s one-minute temperature observations.

If this temperature isn't exceeded by 9am on Wednesday, then Tuesday will officially be Sydney's coldest day since 1984 and the coldest for August since 1962.

The last time Sydney had a day this cold, Neville Wran was the Premier of NSW and Bob Hawke was in his second year as Prime Minister.

Image: Sydney was cold and gloomy on Tuesday. Source: @smitanphoto / Instagram

The city's coldest day on record was 7.7ºC on July 19, 1868 and the coldest day in August was 9.1ºC in 1972. Further west, Richmond had only reached 10.7ºC between 9am and 5pm on Tuesday.

If this isn't exceeded by 9am Wednesday it will also be the site's coldest August day since 1962.