• The weather bureau has confirmed January was Sydney's hottest month on record. (AAP)
The first month of 2017 was not only Sydney's hottest January on record but the hottest month ever in the NSW capital.
Source:
AAP
1 Feb - 1:46 PM 

It's official - Sydneysiders have just sweated through the hottest month on record.

The city's average maximum temperature for January was 29.6C beating the previous mark of 29.5C recorded in 1896, the Bureau of Meteorology said on Wednesday.

Last month Sydney had 11 days when the temperature topped 30C, and five days above 35C, smashing not only all previous records for the month, but for any month since records began in 1858.

"Anyone that's been feeling really uncomfortable can feel 100 per cent justified in their complaints," Bureau of Meteorology climatologist Agata Imielska told AAP.

"It's the warmest month for Sydney."

January's average minimum was 21.6C, breaking the previous January record of 21C in 1991, and the previous average minimum for any month which had been 21.2C in February 2010.

"Only three days dropped below 25C as a maximum in January 2017 and that's the equal fewest on record with January 1994," Ms Imielska added.

The climatologist says Sydney's record-breaking temperatures were due to a combination of strong westerly winds, unusually dry conditions, less-than-average rainfall and climate change.

"One factor is the ongoing warming trend - we've warmed by a degree in the past century and it's not just about averages, we see increases in these extreme temperatures as well," Ms Imielska said.

"It doesn't just go for land temperatures, it also goes for ocean temperatures. In 2016 we saw the warmest ocean temperatures on record."

The persistent heat has been aggravated by dry conditions since October caused by a high pressure system sitting over the Tasman Sea which has increased westerly winds moving over southern Australia.

"We've also had warm offshore sea surface temperatures - that also keeps conditions warmer particularly at night," Ms Imielska said.

"As a result we have seen that back-to-back heat and the lack of relief - the surprising thing is that there haven't been any really cool days."

Sydney conditions are due to heat up again over the next few days with the mercury expected to hit 37C in the city and 43C in the west on Sunday.