Hot one expected for the weekend but forecasters say it will be a mild summer overall

Second day into the new year and 2018 is looking pretty good.

Southern Sydney was basking under warm summer skies with maximum temperatures of around 28 degrees.

Those on summer vacation were making the most of the pleasant conditions with many heading down to the region’s popular waterways and beaches like Dolls Point.

Tomorrow and Thursday are forecast to be a bit cooler with maximum temperatures of 24 and 26 degrees before things really start to get hot on the weekend as another pulse of heat moves across southern Australia.

Many populated regions will cop temperatures close to or above 40 degrees.

Parts of western Sydney may reach 40 and 44 degrees on Saturday and Sunday, respectively, while Melbourne can expect 39 degrees on Saturday.

But the looming heatwave is unlikely to augur an exceptionally hot year for Australia as a weak La Nina in the Pacific will start to tilt the odds to relatively cool and wet conditions for much of the nation, forecasters say.

The longer-term forecast is for a relatively damp start to the year.

The latest Bureau of Meteorology climate outlook (see chart below) for the first three months of 2018 show the odds favour more rain than usual for almost all of the country. 

Rainfall outlook for the first three months of 2018.

Rainfall outlook for the first three months of 2018.

"The cloud and the rain reduces the chance of getting searing heat," Brett Dutschke, a senior meteorologist with Weatherzone, said.

Mr Dutschke said sea-surface temperatures were "still fairly high" – particularly off south-eastern Australia – creating conditions for above-average rain.

Still, the warm end to 2017 – likely to be among Australia's five warmest years in records that go back to 1910 – means any relative easing in temperatures may barely be noticeable for many regions.

La Nina events typically mean eastern Australia turns wetter and cooler than usual, as a strengthening of easterly winds along the equatorial Pacific drags more rain westwards.  

The La Nina, though, is expected to be weak and end by autumn, the bureau predicts.

  • with Peter Hannam