The screening of Finding Nemo will now be held on Friday, January 31.
Council posted the update to Facebook after an earlier post explaining "whilst we expect people would make a splash and get wet anyway, unfortunately our Dive in Cinema equipment can't operate in the rain.
It was due to be the second Dive in Cinema after 250 went along to watch Aquaman last Friday evening.
People who have bought tickets, can either use them on January 31 or receive a refund. Ticketek will contact ticket holders via email and they will have the option to select what they'd like to do.
For those who have a ticket but don't receive anything from Ticketek in the coming days, please call 4931 2879 or email Place.Activation@maitland.nsw.gov.au