Coolest April since 2006 for Aust

Australia has had its coolest April since 2006 but rainfall was still below average across the nation, despite heavy rain in NSW and South Australia.

April 2015 was 0.68C below the long-term national average - the coolest result since 2006 and the 18th-coolest since reliable records began in 1910.

Rainfall was 12 per cent below average nationally even in the wake of the ferocious east coast low that battered NSW last week, a major cloud band that dumped rain across much of SA and southern NSW.

BOM climatologist Blair Trewin said three areas were particularly wet - the storm-hit Sydney-Hunter region in NSW, inland SA and southern NSW, and far eastern Victoria and southeast NSW, which had significant rain after Easter.

"All three of those areas in April rainfall was in the top 10 per cent of totals recorded historically," he told AAP.

Branxton smashed its 152-year-old record for the wettest day and monthly rainfall - 199.4mm on April 22 and 454.8mm for the month, compared to 116.9mm and 340.6mm respectively.

With the exception of Western Australia's Pilbara region, most of northern Australia was drier-than-average as wet season rains stalled.

By comparison, Tasmania had its fifth driest April on record and the Northern Territory also had a dry month but Victoria and Western Australia were close to average.

Nationally, maximum temperatures for April were 1.02C below average.

Most of the northern tropics had warmer-than-average daytime maximums in April - up to 2C above average in parts of the Cape York Peninsula and the Carpentaria coast, Mr Trewin said.

"But conversely they were 1C or more below normal over most of the southern half of mainland Australia and between 2C and 4C below normal over large parts of SA and the interior of WA, including the Pilbara," he said.

Ten Pilbara centres recorded their lowest April maximum temperatures on record, while Learmonth and Karratha had their lowest mean monthly maximum temperature on record - 29.7C and 31.5C respectively/

Minimum temperatures were near average - down just 0.36C - over the continent.

The east coast low was a dominating feature of April's climate, Mr Trewin said.

"Though you get fairly significant east coast lows from time to time that one was probably the most significant in terms of its impact that we've seen since 2007," Mr Trewin said.

"Not only did that produce very heavy rain in coastal NSW, but because it had a very deep southerly circulation on its eastern side it pushed very cool air well north into much of the country earlier in the season than would normally be the case."

WEATHER EXTREMES FOR APRIL:

* Hottest day - 41C at Borroloola Airport, NT, April 6

* Coldest day - minus 1.0C at Mount Hotham, Vic, April 19

* Coldest night - minus 6.9C at Liawenee, Tas, April 20

* Warmest night - 29.7C at Broome NTC AWS, NT, April 1

* Wettest day - 307.5 mm at Maitland Belmore Bridge (Hunter River), NSW, April 22