Guidance is now 3.6-3.8 million tonnes versus the previously flagged 3.6-4Mt.
Bad weather has been a recurring theme for Metro in 2022, with output in May and June also being negatively impacted.
Still, Metro has proactively introduced initiatives to try and reduce "uncertainty and exposure to volatility" by signing new freight contracts and foreign exchange arrangements.
Those moves come with the company also being set, subject to financing, to increase the capacity of the Bauxite Hills operation from 4Mt per annum to 7Mtpa.
Meanwhile, the recent half year is an improvement on the previous corresponding period when Metro suffered an $87 million loss.
Shares in Metro fell 9.5% to 1.9c after the current loss was revealed, capitalising the company at $71 million.
A $25.4 million placement in July priced new shares at 2c each.
