Odds favour an end to Sydney's long dry spell

Those hoping for a long hot mostly sunny summer on the beaches and playing fields of Sydney may be in for some disappointment.

The latest outlook from the Bureau of Meteorology for November to January points to the odds beginning to shift to average or wetter than average conditions for most of south-eastern Australia.

Along with the higher chances of rainfall for the region, including for Sydney, the extra cloud cover will probably moderate daytime temperatures while making nights warmer and stickier than usual.

Cooling in the equatorial Pacific is tilting towards a La Nina, the bureau said this week, conditions that typically favour more onshore, moist winds for eastern Australia.

Even average rain for Sydney, though, would be welcomed by residents worried about the drying out of their parks and gardens. Fire authorities have also been watching anxiously for a break in the record dry spell.

As of Thursday, the city had been on a run of 69 days in a row with less than 2 millimetres of rain falling in the Observatory Hill gauges.

The previous record stint was 64 such days, running from August to October 1989.

The last time there was a drier 90-day spell than the current one was in June-September 1946. During that period, just 24.5 millimetres of rain was recorded at Observatory Hill compared with the 24.8 mm in the current 90-day run, the bureau said.

Relief on the way

Graeme Brittain, a meteorologist at Weatherzone, said the bureau's oldest site had dodged the showers that have dampened most of the city in recent days.

The dry run, though, should be broken in coming days as a dominant high pressure in the Tasman continues to steer onshore winds to the state.

Even so, "there's no real indication of any significant rain on the way in the next couple of weeks" for Sydney, he said.

Sydney Water reports that average daily water use so far this month is running at 1.765 billion litres, up 14 per cent on a year earlier and the most since 2002.

The jump in demand was starker in September when average water demand was 1.722 billion litres, or 25 per cent higher than a year earlier, Sydney Water said.

For November, though, the bureau is predicting some relief in terms of possibly above-average rain for eastern NSW. (See chart below.)

Those odds favouring wetter-than usual conditions increase in December, particularly for the south-east corner of NSW, and eastern Victoria. (See bureau chart below.)

Both those regions have been especially dry so far this spring, stoking concerns about the risks of bushfires.

Not so hot

For the November to January period overall, the outlook is for roughly average daytime temperatures for most of eastern Australia. Tasmania and the Top End are both likely to be warmer than average, the bureau said.

For Sydney, the clearest departure from average maximum temperatures is likely to come next month, with most of NSW likely to be on the cool side compared with the long-run norm. (See chart below.)

December is likely to continue the pattern before January reverts to more average conditions.

In the near term, though, Sydney can expect another week or so of warmer than usual days for October, with most nights also milder than normal.

The same high pressure system bringing showers to coastal NSW will also block any powerful cold fronts that typically bring strengthening winds and shifts in direction that cause fire authorities the most concern.

For Sydney, the next burst of heat is likely to arrive by Friday or Saturday next week, with the mercury likely to climb into the low 30s before dropping back, Mr Brittain said.

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

This story Odds favour an end to Sydney's long dry spell first appeared on The Sydney Morning Herald.