Dyfed Powys Police say they have had reports from all over west Wales about flooding on roads and in houses.
A spokesperson for the police said they had been 'inundated' with received calls from areas including Aberystwyth, Carmarthen and Pembrokeshire.
He advised people to stay inside and avoid driving due to flood water gathering on both minor and major roads.
Traffic Wales says no roads as yet are closed due to the flooding. To check for updates visit the Traffic Wales website.
More top news
Most places will see a dry, bright day with patchy cloud but also some warm sunny spells, and it'll be less breezy than on Friday.
Members of the RMT union are walking out for three days from today in a row over new trains causing disruption to bank holiday services.
The Bank Holiday is here! Which is usually a recipe for wet weather! Yes, we will get our fair share. But it's not all doom and gloom!