A wet weather system has brought heavy rain warnings to the South Island's west, interrupting a settled spell and putting rivers, roads and coastal areas back under watch.

Large swells and worsening driving conditions were also concerns. The system arrived after a relatively settled period for parts of the country.

For West Coast communities used to fast-changing weather, the warnings again highlight the importance of local readiness and clear communication.

Civil Defence and councils have been working with residents and visitors to track the system as it moves through.

The key question is whether saturated catchments can absorb further rain without significant impact.