The flooding devastated homes, livelihoods and communities just as the region began to recover from the 2009 floods.
Associate General Secretary of the Methodist Church in Fiji and Rotuma, Rev Tevita Banivanua, said this most recent event has been the most damaging.
"This was the worst," said Rev Banivanua.
"The big reservoir overflowed and the water levels rose so fast.
"We can't even get to Nadi by road."
Rev Banivanua was particularly concerned for students and children, saying that the government had closed all schools and universities.
Fiji was majorly impacted by floods in 2009, which battered infrastructure and the economy.
Further heavy rains caused havoc as recently as February this year.
UnitingWorld has pledged to launch relief efforts sharing equipment and materials with partners and congregations to assist in rebuilding communities and supporting families.
To make a contribution to flood relief efforts in Fiji, call Uniting World on 1800 998 122