A change in Melbourne's weather forecast has prompted Flemington officials to put 5mm of irrigation on the track ahead of the Melbourne Cup meeting.

The Flemington track will get 5mm of irrigation in the hours before the Melbourne Cup.

There has been criticism the track is too firm but Flemington officials say the decision to put water on the track is because of a changed weather forecast not in response to outside influence.

The Victoria Racing Club racing manager Leigh Jordan and track manager Liam O'Keeffe spoke to the Bureau of Meteorology's head forecaster at 5pm on Monday.

They were told the forecast for rain had been changed and made the decision to irrigate overnight ahead of Tuesday's Cup.