The Bureau of Meteorology's newly released annual climate summary revealed 2016 was the territory's third hottest year, while June to September had the most recorded rainfall for that period.

Mean temperatures were 1.3 degrees above average.

January 13 took out the most sweltering top temperature at 39.3 degrees, just two degrees below Canberra's hottest recorded day three years earlier.

Both top and low temperatures were among the ten warmest years. The 788 millimetres of rain at Canberra Airport was the most recorded in six years and the 12 months were the hottest since 2009.

Senior climatologist with the Bureau Agata Imielska said Autumn was unusually warm, due to falling at the tailend of the super El Nino event that took hold of south-eastern Australia in the summer of 2015 and brought hot and dry conditions.

The El Nino event made it harder for rain clouds to develop and contributed to 46 per cent less rain than average from February to May.

But an unsettled year saw conditions flip and June to September have a record-breaking 127% more rain than average.

"Once the El Nino past, the particularly wet weather resulted from a negative Indian Ocean Dipole event that was one of the strongest on record," Ms Imielska said.

"This brought widespread wetter conditions not just to the ACT but as far as the Great Dividing Range."

A negative Indian Ocean Dipole is when westerly winds intensify along the equator, resulting in above-average winter–spring rainfall over parts of southern Australia.

Looking ahead, Ms Imielska predicted warmer and dryer conditions than average for the next three months.

"But it's too early to tell in the long-term how 2017 will compare to 2016, as we'll need to see what happens to the oceans around Australia."

But what she did know was that Canberrans were yet to face the most scorching days of summer.

They should brace for a hot spell arriving on Sunday with forecast temperatures spiking at 37 degrees on Monday and Tuesday.

Before then, the mercury was tipped to reach between 30 and 31 degrees, while the nights were expected to be mild lows of 14 to 15 degrees.