“High rainfall, potential for more severe flooding beyond the current impacts to the network, strong winds, fallen trees and debris, power failures and fallen power lines and power poles are all concerns which led to operations being halted,” said a spokesman at ARTC, which runs the rail lines.
It said tracks would be reopened when conditions are safe and water levels recede.
The Hunter Valley network serves mines run by BHP Group Ltd, Glencore PLC, New Hope Corp Ltd, Whitehaven Coal, and Yancoal Australia Ltd, among others.
The companies were not immediately available to comment on the impact on their operations.
The Port of Newcastle has two coal terminals with a total annual capacity of 145 million tonnes.
Heavy rains along Australia’s east coast over several days have caused the worst flooding in half a century, with thousands of people being forced to evacuate their homes. The downpour is expected to continue over the next few days, the weather bureau warned on Monday.