The phenomenon's name is a little bit of "false advertising", astronomer Sara Webb told AAP, as the moon won't actually be pink.

However, it will appear 17 per cent bigger and 30 per cent brighter, and will still be "absolutely stunning", she said.

"It's one of those moons that when you're driving along or you're outside that you really like 'woah'."

The moon will begin rising around 5:30pm, and will be at its best until about 7pm.

The phenomenon, which usually takes place every year around April, is caused when a full moon occurs while it is on its closest approach to earth.

"Hundreds of years ago the Americans used to call it the pink supermoon because a beautiful wildflower would bloom around the same time, so they would associate that with big bright full moon," Ms Webb said.

This year Australians will be treated to two supermoons, with another due on May 26.

"We have one full moon as it is entering its closest point and one full moon as it is exiting its closest point ... so it is just a lucky coincidence," she said.

The second will be arguably better than the first, Ms Webb said, as it is a blood supermoon.

"This one is not false advertising in the name. It actually is bright red and it's because it's going to happen during a partial lunar eclipse."

Australian Associated Press