Many of Sydney's commuters had a sweltering journey to work today, but the journey home won't be much more comfortable after a delay in the expected cool change.

Sydney's temperature peaked at 37.8 degrees just before 2pm, and had eased back to 34 degrees by 4pm.

A gusty cool change is on the way but will not arrive in the city until about 5pm after stalling earlier this afternoon, Tristan Meyers, a meteorologist from Weatherzone, said.

Areas to Sydney's north, such as Williamtown, reached 41.6 degrees, in line with the Bureau of Meteorology's forecast for the region:



While the change may not be as strong as last Friday's - after Sydney's top reached 40.9 degrees - it is likely bring wind gusts of 70-80km/h, Brett Dutschke, senior meteorologist with Weatherzone, said.

​Fire dangers will be severe for much of the region, the bureau said in a fire warning alert. It has also issued a severe weather warning for damaging winds for the Illawarra, Snowy Mountains, Southern tablelands and the ACT.

Total fire bans are in place for the Greater Sydney, Greater Hunter, northern slopes and north-western regions of NSW, the Rural Fire Service said.

There is only a small chance of a shower with the change, Mr Dutschke said.

"We're expecting the winds to be less than gale force" ahead of the change, Andrew Haigh, a bureau forecaster, said.

Adding to the day's torments, pollen levels were forecast to be extreme for hayfever sufferers, Weatherzone said.

Hot spring

The rest of the month will be much milder with maximums of 23-27 degrees forecast, before Sydney's temperatures rise back into the 30s from Tuesday, the bureau predicts.

The bureau on Thursday also released a report on how 2015 is shaping up after the World Meteorological Organisation predicted this year will be the hottest for global temperatures.

So far this year, Australia is running at its equal-sixth warmest, while the running 12-month average is the fourth-hottest on record.

Even if November and December matched 1990 as the warmest for those two months, 2015 would come in as the fifth-hottest in national data going back to 1910.

"We estimate that [2015] is likely to sit in the top 10 warmest years on record, and could end in the top six," the bureau said.

The hot end to this year's spring across many parts of Australia will likely bring it close to breaking national heat records for a third year in a row.

As the following bureau chart shows, October was almost 3 degrees above the norm for mean temperatures - the highest departure from long-term averages for any month on record.

For Sydney, last Friday's maximum fell 0.9 degrees shy of the 41.8-degree record for the city set in 1982.

A reading on Thursday of 38.8 degrees or warmer would give Sydney its second top-10 hottest November days in 156 years of records - in less than a week.

Weatherzone is owned by Fairfax Media, publisher of this website.