Tropical Cyclone Ula is crossing Fiji's southern Lau group and may intensify.
The small islands of Kabara, Namuka, Fulaga, Ogea, Vatoa and Ono-i-Lau are warned to expect destructive storm force winds of up to 155 kilometres an hour.
The category three system, which at its centres has average winds of 150 kilometres an hour and gusts of more than 200 kilometres an hour, is tracking southwest between the islands of Kabara and Ono-i-Lau.
The cyclone has slowed and the Fiji Met Service says it may intensify.
By about seven o'clock tonight Cyclone Ula is forecast to get within about 65 kilometres of Ono-i-Lau.
Fiji's education ministry has advised all school evacuation centres to be on standby for immediate activation.
Hurricane force winds and phenomenal seas are forecast for the area within 25 kilometres of Ula's centre.