"It's going to be a tricky day tomorrow because it looks like it's going to be sunny but we'll do the best we can," he added.
Perez agreed with his team mate's downbeat assessment of McLaren's current standing going into the first race of the season.
"Tomorrow may be a tricky day for us because our car isn't yet as competitive as it'll become, but our aim will be to score points with both cars so as to keep in touch with the teams who currently appear to be a little way ahead of us in terms of performance," Perez said.
And in the meantime, as the rain continued to fall in Albert Park on Saturday evening, Button's sympathies lay with the fans who had stuck it out on the wind- and rain-lashed grandstands without recourse to the cost team garages that he and Perez enjoyed.
"It was even worse for the fans," said Button when asked about how the disruption of the stop-start qualifying session had been for him. "[They've] been waiting excitedly for qualifying all day long and then had to sit in the pouring rain with no on-track action to entertain them.
"I'm very sorry for them, because the fans are what all sport is ultimately all about, but I hope we can make it up to them tomorrow by putting on a really exciting race."