It won't be enough to fix Otago's drought in one hit, but there is some rain on the way for the region.

MetService says a low pressure system moving in from the Tasman will bring rain to Otago and Southland, and it should begin overnight.

Forecaster John Crouch says wet weather is expected to be around for a while.

"Parts of Southland and Otago probably will see some decent rain into early next week, particularly into Monday and Tuesday."