RNZ Pacific's correspondent in Port Vila said there's flooding in some areas of the capital and road blocks caused by fallen trees.
Hilaire Bule said some parts of Port Vila were enduring power cuts.
Irene has caused mainly damage to the fruits trees such as avocado and banana.
The Vanuatu Meteorology and Geo-Hazard Department said Irene is expected to hit the Island of Tanna, in south Vanuatu at midday Thursday local time.
A red alert is in place for Tafea, Shefa and Malampa provinces, while Penama and Sanma provinces are on yellow alert.