It's the second time in a month heat has affected train services along the Albury line, after trains were replaced by buses on November 21 due to Victoria's code red fire danger rating.

Neither Australian Rail Track Corporation, which manages the track, or V/Line could say how many times extreme heat timetables or policies were enacted last summer, each referring the question to the other.

An ARTC spokeswoman said staff generally start heat-related track patrols when consecutive days of 38 degrees or higher temperature are forecast.

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"The ARTC North East rail line has concrete sleepers and heavier, continuously welded rail which offers improved stability and more reliability in hotter weather than those that use timber sleepers elsewhere," she said.

"In line with our track stability management plan, which covers instances of high temperatures, ARTC monitors forecasts closely and undertakes extra track inspections to ensure safety."

V/Line chief executive James Pinder said extra precautions were taken when forecast temperatures exceeded 36 degrees due to steel tracks expanding in the heat.

"Our team closely monitors the weather forecast and activates the extreme heat timetables across the network when necessary," he said.

"On really hot days, some services will run at slower speeds or may be replaced by coaches for all or part of the journey and these service changes are reflected in the extreme heat timetables."

Copies of the extreme heat timetables can be downloaded from the V/Line website or collected from a staffed station.