Santa looks set to bring Melburnians a mild and mostly sunny Christmas Day.

Canberrans can expect a cool change from Monday after a warm and windy weekend.

Slow-moving Typhoon Hagupit has weakened as it churns across the central Philippines islands, easing fears of widespread mass destruction, but officials warn the storm could still bring severe flooding to the low-lying capital Manila.

"Mate, I lost about 100 heartbeats I reckon in that split second, and got a few more grey hairs."

NSW will likely cop its third buffeting from an east coast low in five weeks but there is some good news.

Canberra hasn't seen any heatwaves this summer, but that doesn't mean it hasn't been a hot one.

The Bureau of Meteorology has warned of possible flash flooding in the Queanbeyan and Molonglo rivers on Friday.

Brisbane's sweaty masses are set for a slight reprieve leading into the weekend, with the high temperatures and sticky humidity both set to become that little more bearable.

Global temperature records continue to tumble, with August easily the hottest in 124 years of data, Japan's Meteorological Agency says.

If Thursday hits its predicted peak it will be the ACT's longest March heat spell on record.