THE strong east coast low, also known as an east coast cyclone, that battered eastern Australia, and good rains across southern regions combined in April to break a run of warmer-than-average national weather.
Mean and maximum temperatures were cooler nationwide by the biggest anomaly since March 2012, coming in at 1.02 and 0.68 degrees below the long-run average, according to the Bureau of Meteorology. For mean temperatures, April delivered the first below-average reading since February 2014. Visit FarmOnline Weather for more updates and information
Warm sea-surface temperatures in the Indian Ocean contributed to persistently wet and cloudy conditions over large parts of the interior, especially in Western Australia, Agata Imielska, a senior bureau climatologist, said.
The big east coast low that hammered Sydney and central NSW last month brought the wettest April for the state since 1990.
For Sydney alone, the big low lifted rainfall to 370mm for the month - almost triple the average. The three days of the storms were also the city's longest cool spell in April since 1983, the bureau said.
Even with that chilly burst, the city managed to maintain its run of above-average temperatures. Average maximums came it at 0.3 degrees above average, while minimums were 0.6 degrees on the warm side.
The last time Sydney had a below-average month for maximum and minimum temperatures was March and May 2012, respectively, Ms Imielska said.
The city recorded rain on 23 days last month, the equal second highest for April and the most rain days since 1923, the bureau said. A typical April would have 13 rainy days.
Even with the widespread rains, national rainfall was about 12 per cent below average because of drier conditions across the country's north, while Tasmania had its fifth-driest April.
"The current outlook is favouring wetter conditions across large parts of Australia," Ms Imielska said.
Those conditions include unusual warmth in the Indian Ocean, which is helping to drive moisture streams across the continent.
Those wetter - and cooler - conditions - aren't likely to last, however.
As the bureau noted earlier this week, there remains a 70 per cent chance of an El Nino emerging later this year in the Pacific.
During El Nino years, temperatures in the eastern equatorial Pacific are relatively warm compared with those in the west, a set-up that tends to drag rainfall away from Australia.
"We are expecting an El Nino to develop, so the wetter-than-average conditions aren't likely to continue into the winter and spring," Ms Imielska said.