Sydney has recorded its wettest August in 27 years, and there’s more rain coming

Sydney’s wet winter is showing no signs of letting up, with conditions expected to worsen on Wednesday and Thursday as the city smashes rainfall averages.

After a brief reprieve for a sunny weekend, the city will be drenched again for the rest of the week. The Bureau of Meteorology is forecasting up to 30mm on Wednesday and 60mm on Thursday, with a chance of a thunderstorm.

While the heaviest of the downpours will ease by Friday, light showers are expected to continue into the weekend.

In the first three weeks of the month, 241mm of rain has fallen in Sydney, four times the month’s average, making it the wettest August in more than 25 years.

“We’re certainly going to see those numbers continue to climb because there is more rain in the forecast for the next few days in Sydney,” Bureau of Meteorology senior meteorologist Angus Hines said.

“Today will be a wet day, tomorrow will be a wet day. Could well see some showers lingering into Friday as well.”

The August rainfall, based on the amount recorded at Sydney’s Observatory Hill, is still a long way from the 1998 monthly record of 482mm.

Winter is not generally associated with heavy rainfall in Sydney, with the highest averages being in the autumn months between February and June. The combination of the cold, wind and rain has made for unpleasant conditions.

“August is typically one of the drier times of the year, so having several different wet weather events all come through in quick succession and all drop a really notable dose of rain on and around Sydney is certainly pretty unusual,” Hines said.

The relentless rain has created a flood risk across much of the state.

Speaking about the “significant weather event” at a press conference on Wednesday, NSW SES Deputy Commissioner Deb Platz said “compounding events” had heightened the risk for already fatigued communities.

“We know that our catchments are saturated. We know that this year we’ve seen significant weather events, significant flooding and a lot of damage,” she said. Across the state, more than 20 warnings have been issued by the SES.

“Depending on where this rain falls and how much of it falls, the flooding from this weather system is likely to commence overnight and tomorrow,” she said.

Steve Bernasconi, the Bureau of Meteorology’s manager of hazard preparedness, said the rain event had created a risk of flooding across a large swath of the state, including the Mid North Coast, Northern Rivers, Northern Tablelands, Northwest Slopes and Plains, and parts of the Hunter and Greater Sydney regions.

“There’s not necessarily enough rain to create a severe weather warning, but the catchments are so wet that this sort of rain event has the potential to create minor to moderate flooding, with isolated majors, depending on where significant rainfall falls over a catchment.”

Platz said the back-to-back weather events risked complacency, but urged people to download the Hazards Near Me app and follow SES advice.

“We know that the community is tired, our volunteers are tired,” she said.

The conditions are being driven by a weather system in the upper atmosphere.

“If you went up in a weather balloon or a hot air balloon five or 10 kilometres above our heads, you’d see what we call an upper-level low-pressure system, which is just sitting over northern NSW,” Hines said.

He said the relatively warm oceans off north-east NSW and Queensland were allowing the system to “pull in lots of moisture and humidity”.

“We’re seeing a lot of that humid air getting dragged in and over eastern parts of the country, and that’s why it’s so cloudy, and we are also seeing a lot of rain.”

NSW SES Assistant Commissioner Colin Malone urged people not to drive through floodwaters. Earlier this month, a Chinese tourist died after the car she was a passenger in was swept away by floodwaters near Cessnock in the state’s Hunter region.

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