June has been the coldest first month of winter in nearly 20 years for some parts of NSW, while Canberra is headed for its coldest run of nights in June in living memory experts say.

The combined average of minimum and maximum temperatures in the nation’s capital reached just 5 degrees for June, making it the coldest June since records began in 1939.

Cooma in NSW’s south has also experienced a run of bitingly cold nights.

Average minimum temperatures at Cooma Airport sank to -3.5 degrees, the coldest June minimum temperature since 1991.

Goulburn followed closely behind with an average combined temperature of just 6.2 degrees, only marginally warmer than Canberra, for the month of June.

The final night of the month is expected to be similarly cold, with average temperatures not expected to get any higher as records look to be shattered.

From tomorrow, cold conditions are expected to ease over NSW’s east coast thanks to a humid easterly airstream developing offshore.

It will however remain cold across central and western NSW.

Minimum temperatures in Canberra are forecast to stay icy late next week, plummeting to -4 degrees on Friday and Saturday.

Melbourne is expected to be slightly warmer than its east coast counterparts with temperatures headed for tops of 15 degrees by Saturday.

The wintery blast will bring gusts of up to 100km/h, forecasters say, with rainfall totals reaching 300mm possible in some areas, potentially causing flooding.