Sydney just received an entire year’s worth of rain in less than six months following yet another sodden weekend in the city.

The familiar sight of dark clouds and persistent rain late last week saw Sydney pick up 60 mm of rain during the 48 hours ending at 9am on Sunday, June 23.

This latest bout of heavy rain brought the city’s running monthly total up to 361 mm, which is more than double the long-term monthly average and Sydney’s wettest June since 2007. It’s also Sydney’s 6th wettest start to winter in records dating back to 1859.

The weekend rain also increased Sydney’s running annual total to around 1240 mm*, pushing it above the city’s long-term annual average of around 1213 mm.

This is only the 10th time in 166 years of records that Sydney has exceeded 1200mm of cumulative rainfall by this point in June, with 2024 now ranking as the city’s 8th wettest start to a year on record. The wettest January 1-to-June 24 period on record was 1543.8 mm in 2022.

Sydney’s exceptionally wet first half of 2024 was underpinned by frequent periods of easterly winds that drove moisture-laden air from the Tasman Sea towards NSW. These onshore winds were more persistent than usual due to abnormally high pressure to the south and southeast of Australia, particularly in May and June. The winds also carried more moisture than usual thanks to above average sea surface temperatures over the Tasman Sea.

Looking ahead, warmer-than-average sea surface temperatures are predicted to persist in the Tasman Sea during the rest of winter. While this doesn’t guarantee more abnormally wet weather, it does increase the potential for rain in the coming months.

Image: Forecast sea surface temperature anomaly in July 2024, according to the ECMWF SEAS5 model.

*Some of the rainfall observations used to calculate Sydney’s year-to-date rainfall in this article were estimates from the Bureau of Meteorology. These estimates were to account for missing observations due to instrument failure at the Sydney Observatory Hill Automatic Weather Station. The following rainfall estimates were used:

• 160 mm in the 24 hours ending at 9am on April 6
• 35 mm in the 24 hours ending at 9am on February 20