Well I certainly have never known an April as hot as this. We're only half way through, of course, but I thought I'd do a quick comparison of the first half of the month (April 1 to 15) this year with the same half-month period from 1995 to 2017.

In each case, the historic, 23-year figure is first, followed by this year's, in square brackets.

Average temperature 19.8 [22.6]
Average daily maximum temperature 24.2 [26.9]
Average overnight minimum temperature 16.3 [18.7]
Highest maximum temperature 30.5 [30.6]
Lowest minimum temperature 7.8 [16.5]
Lowest daily maximum temperature 16.1 [24.8]

Hard to believe we're only six weeks away from winter.

At Manilla, NSW, this April's mean temperatures 1st to 17th are Max 31, Mean 23, Min 14.
At the usual rate of Autumn cooling, I expect the final April means to be 1 degree lower, that is: Max 30, Mean 22, Min 13.
I set up my April normals using the decade April 1999 to March 2008 as: Max 26, Mean 18, Min 11.
The April anomaly values that I expect for this April are:
Max +4, Mean +4, Min +2.
That will make it about one degree warmer than my previous warmest April: 2005.
Last April (2017) was my fourth coolest: more than one degree below normal.

In 20 years, the rise in the April linear trend is trivial.
A fitted quartic trend line is low in 1999 and 2011, and high in 2003 and 2018. The quartic trend line for Max is a couple of years in advance of the quartic trend line for Min.

Weatherzone has a news item, sourced to "ABC", about this April warmth. It includes statements by Blair Trewin.
I expect it will just get lost, like all old news.