The brightest supermoon in 68 years is expected on Monday night, with the moon already looking impressive on Sunday evening.

Poor weather has hindered the chance of sighting the closest supermoon since 1948 but astronomy fans say the view is still worth a look on Tuesday night.

The supermoon is a full moon that coincides with the point in the moon's elliptical orbit when it is at its closest to the Earth. It was set to be at its fullest on Monday, beng the closest full moon to the Earth since January 1948.

The next time the full moon would be as close will not be until November 2034.

Palmerston North astronomical society president Ian Cooper said even if the moon isn't visible due to poor weather on Monday night, the following night it would only have diminished slightly.

"It would be just a little bit down. 100 per cent tonight, tomorrow, 98 per cent, but it will still look pretty impressive."

Cooper said the contrasts in proximity to Earth come down to inches at times.

"There's a feeling when you look at it, it definitely looks more impressive."

On Tuesday night from 8.50pm onwards Cooper said it should be visible towards the north east of Palmerston North towards the Manawatu Gorge.

"The closer you get to midnight the higher the chances.

"When it really is a full moon the sunlight is bouncing right back at us so it's way brighter."

Cooper suggested trying to see it on Monday night if people were up and about.

"If people are out and about and getting a bit shook about and maybe need to go outside ... it might reveal itself."