The forecast maximum of 36 degrees is warmer than any day the capital had last summer, and signals a return to more average hot summer conditions, according the Bureau of meteorology's Sean Carson.

"The last two summers combined we've only had three days in excess of 35. On average we should have 12 to 13 days above 35 every summer," Mr Carson said.

"We should be back up towards that average again this year."

Although Canberra will officially be the hottest capital city today according to forecasts, Mr Carson said there will be plenty of hotter places around.

South Australia, Victoria and western NSW have all been hit hard by a mass of hot air, with Melbourne last night recording its hottest November night in 111 years, and Sydney-siders being warned today of an approaching heatwave from the west which will push temperatures above 40 degrees.

Canberra's overnight minimum temperature of 18 degrees was 9 degrees above average. It wasn't until after 7.30pm that the mercury finally dipped back below 30 degrees.

The relief is on its way tomorrow, with a cool change still forecast to make it to the capital around lunch time of mid-afternoon. But Mr Carson has warned it will only bring "subtle relief".

"The key is that the really hot air is only going to shift back inland a little bit," Mr Carson said. "It'll only take another high in the Tasman to drag that hot air back down."

The temperatures for next week are expected to hover in the mid-20s.

Despite the hot temperatures, Mr Carson called on Canberrans to embrace the return of the warm weather.

"After two lousy summers, we should get out and enjoy it," he said.