Tropical Storm Arthur struck the Central American country on 31 May and dropped more than a foot of rain over the next four days, causing flooding and mudslides.
Of the people who died, three were members of the same family who became trapped in their house. An eye witness said: "The water just came right up and picked up their house, took it down and mashed it up."
A further two people died while fleeing to find safety in the middle of the night.
USPG Mission Companion the Rev Malcolm Lambert reported: "The rain has come down in torrents, with thunder and strong winds on the coast. Several villages are completely under water, waiting for the floods to recede.
"In one village, almost everyone lost everything. The houses were built on stilts, but the flood water was too high, and everything is water and mud soaked.
"The media have concluded this is Belize's worst flooding in 40 years and the country's worst natural disaster in at least two decades."
Rev Lambert reported that a major bridge and a 20-feet wide section of a major road had been washed away by the currents. Emergency services and the British Army garrison are working hard, he said, to establish a temporary river crossing and make the road passable so that food and water can be taken to the area.
"At the moment, they are relying on just a few helicopter flights," he said. "Please remember the situation and people affected in your prayers."
The Rt Rev Philip Wright, Bishop of Belize, said: "The government and other agencies are assisting families with rebuilding their homes and repairing damages to property.
"The Anglican Diocese of Belize welcomes the opportunity to play its part in assisting the people of Belize and helping them to get their lives back to normal."
A grant of £1,000 from USPG will help the Anglican Church in Belize to provide victims with drinking water, food, clothing, blankets and toiletries.
