THERE’S something missing from our weather.

Not the heat, the eastern states have just sweated through their hottest September days ever. And not the snow, which was pummelling the ski resorts until just a few weeks ago. There’s been no lack of gale force winds either.

What’s missing is something we should have been getting plenty of during winter — rain. For almost three months now, it’s been Australia’s unexpected big dry.

Winter 2017 was not only the warmest in Australia since records began, more than a century ago, but was also in the top 10 of driest ever.

“Hobart, Melbourne, Canberra, Sydney and Brisbane have been very dry, significantly below average. The grass is dying,” Sky News meteorologist Tom Saunders told news.com.au.

Only Perth and Adelaide have escaped the parched conditions.

This morning there's 98 fires across NSW, with 25 not yet contained. Total fire bans in four areas today from Hunter to Qld border. #NSWRFS pic.twitter.com/b6Be4eDmjZ — NSW RFS (@NSWRFS) September 24, 2017

More than 270 bush and grass fires this weekend. There's now been more than 2300 fires this month. Warm, dry conditions to continue. #NSWRFS pic.twitter.com/A0sq79cZ2J — NSW RFS (@NSWRFS) September 24, 2017

What’s concerning forecasters is why it’s dry at all. Usually a prolonged spell without rain would be due to the presence of an El Nino or a positive Indian Ocean Diploe — two of the strongest drivers of Australia’s climate. But both are taking some time out on the bench.

Meteorologists say climate change means above average temperatures and drier than usual conditions across many parts of Australia are now the new normal. Its effects can already be seen with crisp vegetation enabling an early start to the bush fire season. More than 200 have erupted in NSW this month.

A new analysis has also warned of an increased risk of severe weather in the coming months.

“It’s been the driest start to spring in Sydney since records began in 1859 with only 0.2mm of rain which you would barely notice,” said Mr Saunders.

“But this dry spell actually started three months ago. Since June 21, Sydney has only had 38.6mm of rain when the average for that period would be 291mm.”

Over the same period, Brisbane has seen 11.2mm of rain with more than half of that falling just last week when one thunderstorm barrelled through the city. More than 100mm of rainfall would have been expected.

With the Indian and Pacific Ocean climate drivers absent, Australia’s lack of rainfall is down to local conditions.

Higher pressure has squatted above a huge expanse of Central and Northern Australia for months, doing its best to ensure we get blue skies and little rain, Mr Saunders said.

“One of the reasons for pressure higher than normal is climate change”.

Whether the big dry will continue is up in the air. In its most recent seasonal outlook, the Bureau of Meteorology said there was a 50/50 chance of it being wetter or drier than average with opposing climate drivers in the Indian and Pacific oceans potentially cancelling one another out.

But Mr Saunders was more optimistic: “The good news is that as temperatures warm up that will allow the pressure to start dropping so we’re expecting it will return to normal rainfall.”

El Nino’s opposite phase, the La Nina, may also make an appearance. Even if it’s a weak La Nina, it may still be enough to help bring the rainfall back closer to average levels.

Despite the big dry, an exceptionally wet 2016 winter means dam levels remain high so the prospect of water restrictions is still some way off.

However, even if the rain does make a reappearance we’re still in for a shocker of a severe weather season during the spring and summer months.

An analysis by Sky News predicts an increased risk of thunderstorms, bushfires, heatwaves and tropical cyclones.

Mr Saunders said another warmer than average season was to be expected.

“The ongoing heat anomalies of recent years will almost certainly continue as global warming becomes an ever more prevalent background influence on Australia’s climate.

“Our country no longer requires El Nino conditions to ensure high record temperatures, prolonged drought and widespread bushfires,” he said.

El Nino or no El Nino, most years now have the potential to break weather records, Mr Saunders said.

HOW WILL YOUR CITY FARE DURING THE SEVERE WEATHER SEASON?

Sydney

Warmer than average temperatures; no heatwaves; up to 22 severe thunderstorms; close to average rainfall.

Brisbane

Warmer than average temperatures; no heatwaves; up to 28 severe thunderstorms; above average rainfall.

Darwin

Warmer than average temperatures; no heatwaves; close to average rainfall.

Perth

Warmer than average temperatures; 1-2 heatwaves; up to 7 severe thunderstorms; close to average rainfall.

Adelaide

Warmer than average temperatures; 1-2 heatwaves; up to 8 severe thunderstorms; close to average rainfall.

Hobart

Warmer than average temperatures; no heatwaves; up to 6 severe thunderstorms; close to average rainfall.

Melbourne

Warmer than average temperatures; 1 heatwave; up to 12 severe thunderstorms; close to average rainfall.

Canberra

Warmer than average temperatures; 1 -2 heatwaves; up to 18 severe thunderstorms; close to average rainfall.

benedict.brook@news.com.au