A Severe Thunderstorm Warning for Heavy Rainfall is now in force for interior and southeastern part of Viti Levu including Sigatoka through Navua-Suva-Nausori up to Tailevu, southern Bua and Cakaudrove Province.
A trough of low pressure affects parts of Fiji.
The Nadi Weather Office says daytime heating has contributed to the development of the thunderstorms which are expected to become severe and can lead to heavy rain.
They say severe thunderstorms are expected to produce heavy rain which may lead to flash-flooding of low-lying areas in the next few hours.
People are advised to keep clear of flooded creeks and drains, don't walk, ride a bike or drive through flood waters, unplug computers and appliances, stay indoors away from windows and keep children indoors and stay vigilant and monitor conditions.
The Weather Office adds that thunderstorm activity with heavy rain and intense lightning is expected until late afternoon or evening.