Cyclone Ului, which has winds at its centre of up to 300 kilometres an hour, is expected to hit the Solomon Islands group of Rennell and Bellona about midnight tonight.
The islanders have been told to expect hurricane force winds and coastal flooding.
The spokesperson for the Solomon Islands National Disaster Centre, Julian Makaa, says this is the strongest cyclone that has approached Rennell and Bellona.
"By midnight it should be closer to two hundred or more winds [kilometres per hour] so we have already been in contact with them since Thursday to warn them and ask them to take precautions and we are just hoping for the best, because this part is in the Cyclone's path."
He says Honiara and other parts of Solomon Islands are already experiencing heavy and wind and this is expected to worsen through Monday, though Cyclone Ului is forecast to head to open water after passing Rennell and Bellona.