NeSI does publish service incidents and scheduled maintenance via status.nesi.org.nz.
Interested parties are invited to subscribe to updates (via SMS or email). All new NeSI users will be automatically subscribed with the option to unsubscribe from some or all components listed on status.nesi.org.nz.
The support.nesi.org.nz homepage does also show current/upcoming incidents.
The site status.nesi.org.nz lists the operational status of all critical components of the NeSI High Performance Compute and Storage Service.