Perth had its coolest winter for decades and Western Australia's South West was one of the few areas in the world that experienced below-average temperatures in 2016, according to the Bureau of Meteorology's (BOM) Annual Climate Statement.

Last year's winter was the coldest since 1993, with an average maximum of 18 degrees Celsius, and a minimum of 8.1C.

However, BOM climate liaison officer Glenn Cook said this should not influence perceptions of climate change.

"That's a common misconception that short-term variability is related to longer term climate change — and it's not," he said.

"As climatologists we expect to see variations from year to year, from month to month, season to season, and we expect to get cooler than normal conditions into the future.

"But they are much less common than the warmer-than-normal conditions, we've had a very warm, really record-breaking period over the last five or so years, with temperatures warmest on record.

"The overall trend is upwards."

WA was the only Australian state to experience below-average maximum and minimum temperatures across 2016.

Annual maximum temperatures were the coolest for more than 20 years at Perth Airport, Bickley and Swanbourne.

Marble Bar in the Pilbara, WA, often breaks record temperatures during the wet season. ( ABC Open contributor quietachiever )

Daytime temperatures during winter were the coolest on record at the Perth Metro observation site, which includes 22 years of records, and the coolest for more than 20 years at many other sites.

Mr Cook said one of the key factors in 2016 was the temperature of the waters off the south-west coast.

"What we saw was very cool sea surface temperatures off our coast in the South West, and they affected the temperatures over land," he said.

"Those sea temperatures have gone back to normal now, so I wouldn't expect these sort of conditions to continue into the future, I would expect it's more of a 'one-off' type year."

While there was a prolonged period of cool and cold nights in the South West, 2016 was a very warm year in northern WA, lifting the average for the state as a whole.

The northern dry season was described as "unusually wet" in the Kimberley.

Perth Metro's rainfall in 2016 was close to average.