A hotter than usual start to summer is predicted for most of Australia, while a dry spring is expected to turn into rainfall for the east coast.

The Bureau of Meteorology forecasts opposing weather drivers from the Indian and Pacific oceans will compete in October to December.

BOM senior climatologist Dr Lynette Bettio said the drying influence from the Indian Ocean was likely to cancel out the slightly wetter influence from the Pacific.

“This means there is an equal chance of wetter or drier than average conditions across Australia,” Bettio said on Thursday.

Daytime and night temperatures are expected to be warmer than average, especially across the north and south-east of Australia. Nights are predicted to be cooler around the Great Australian Bight.

BOM senior hydrologist Paul Feikema said there had been well below average rainfall across most of the country.

“Some key agricultural regions of New South Wales and Queensland have only had a third of their normal September rainfall,” he said.

Early spring heat had also left parts of central NSW, southeast Queensland and Western Australia with serious rain deficiencies, he added.

Australia recorded its hottest September day on record this month on 22 September, when Adelaide reached 30C and Darwin hit 35C.

The next day was the hottest September day on record for New South Wales, where the temperature in Penrith, in Sydney’s west, climbed to 37C.

Australia recorded its hottest July on record this year, with a mean maximum temperature 2.62C above the average maximum temperature.

It was also the driest Australian winter in 15 years, as well as the driest June recorded in Victoria.

“Drier conditions in recent months have resulted in dry water catchments across parts of southern and eastern Australia,” Bettio said.

The weather bureau forecasts sea surface temperatures in the Pacific to possibly reach La Niña thresholds towards the end of the year, which typically bring wetter conditions to northern and eastern Australia.