The CFA's latest all clear update replaces any advice messages that have been previously issued.

UPDATE 3:15pm: A grass fire at Western Highway, near Great Western has been brought under control.

The Great Western Highway has re-opened to traffic in both directions.

A reduced speed limit is in place while firefighters continue to work in the area

EARLIER: An advice message has been issued for a grass fire at the Western Highway, near Great Western that has yet to be controlled.

The message has been issued for Ararat, Armstrong, Black Range, Garden Gully, Great Western, Norval, Rhymney.

The grass fire has crossed the Great Western Highway, and the Great Western Highway is closed to traffic in both directions.

Emergency services said the grass fire currently posed no threat, but encouraged people to stay informed and monitor conditions.

Five vehicles were responding to the incident, with emergency services encouraging people to keep the road clear.