Sydney has received an unprecedented amount of rain so far this year, with 2022 currently the wettest year on record for year-to-April rainfall totals.
Below you can see the cumulative rainfall for 2022 in context with historical averages. The purple shaded section indicates wetter than average years, so if the red line for 2022 goes above this, it indicates an unusually high level of rainfall (the Top 10% of years by total rainfall).
It also shows that the current rainfall received in 2022 is much higher than the median rainfall for all years between 1900 and 2022:
The heavy rainfall has resulted in flash flooding in some areas, and the Nepean river flooding in the city’s south, with residents ordered to evacuate. The Hawkesbury river at Richmond is also flooding, with the Bureau of Meteorology warning that the river height is likely to exceed the major flood level around 10:00am Friday and may peak around 11.8 metres.
This chart shows 2022 compared with all other years of rainfall (starting from 1900 for those areas with pre-1900 records):
The state has been hit by repeated flooding in recent months, with the northern rivers area devastated by two deluges within weeks and Sydney drenched in its wettest March on record.
The bad weather has been driven by a strong upper trough over the centre of NSW, working to deepen another trough sitting off the coast.
