The Solomon Island Disaster management office says three people have reportedly died and eight others are missing as a result of flooding.
Julian Makaa of the Disaster management office says heavy rain has caused devastation in northwest Guadalcanal and on Savo Island.
He says homes and bridges have been swept away.
"And eight people are reported still missing, three unconfirmed deaths and several injuries. The unconfirmed deaths were reported on the Guadalcanal that's two of them and the, one, on nearby Savo Island."
Julian Makaa says the office is working alongside the Guadalcanal disaster unit and police who are preparing evacuation plans and conducting damage assessments in the affected areas.