The previous record summers were about one degree warmer than the average, underscoring how anomalously warm the summer just ending has been.

The heat was widespread, with NSW, Victoria and Western Australia among the regions posting a record-hot summer.

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December and January were the hottest on record nationally and February will come in among the top five warmest. January alone registered eight of the 10 hottest days recorded based on area-averaged heat.

Rainfall was about 30 per cent below average, making it the driest summer since 1982-83, a season affected by a strong El Nino event. Conditions in the Pacific were at near-El Nino levels this summer, too, but temperatures were about one degree higher than that season 36 years ago.

Despite the heat and intensifying drought, the bushfire season has been less severe than might otherwise have been expected given the temperatures. Fires were largely in areas remote from the main cities, such as in Tasmania, east Gippsland and northern NSW.

"We had very stagnant conditions, with sub-tropical or even tropical heat over the whole country for most of the three months," Dr Jones said.

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"There were almost no fronts and a lack of cold coming up from the south."

Only a couple of regions had notably wet spells, such as north-western Victoria in December and the record rainfall that drenched much of north Queensland in an area from Cloncurry to Mt Isa and east to Townsville.

Most of northern Australia, however, had "a very poor wet season", Dr Jones said.

The bureau will release its updated seasonal outlook for autumn on Thursday. Its initial report two weeks ago indicated above-average heat and below-average rainfall would extend into the March-May period for much of the country.

The agency will also release its full summer reports, including for the state capitals, on Friday.