It would appear that Green Day spent the weekend recording in Australia, ahead of their national tour.
A photo uploaded to Instagram by producer Charlie Young on Saturday shows Billie Joe Armstrong standing near a Vox AC30, presumably between laying down guitar tracks. There is a drumkit set up, and the picture was taken in Perth studio Crank Recording. The caption suggests this is a Green Day recording, not one of Billie’s solo projects, and considering the band played Perth Arena on Sunday, this would be more than likely.
The band’s last album, Revolution Radio, only came out in October, so unless the band are planning another three-albums-in-a-year style run, we probably won’t be hearing whatever Billie and co. laid down in sunny W.A. for some time yet.