Strong winds developing in the South Island today could potentially topple trees and damage powerlines, the MetService warns.

The winds come courtesy of a front moving north over the island today and tomorrow, and may reach up to 130km/h in exposed parts of Fiordland, Southland, Otago and Canterbury.

The MetService said motorists, particularly those with high-sided vehicles such as trucks, campervans and caravans, needed to be wary of hazardous conditions.

Heavy rain and thunderstorms in Fiordland and Westland today and tomorrow could also lead to water levels rising significantly in rivers on both sides of the Southern Alps.