Macarthur Coal (ASX:MCC) has cut its first-half profit guidance by 18 per cent after wet weather affected coal mining operations and due to a stronger Australian currency.

The Brisbane-based company has downgraded profit for the six months to December 2010 to a range of $97 million to $102 million. This compares with guidance given in October of $115 million to $125 million.

Saleable production will fall to 2.4-2.5 million tonnes from 2.5-2.7 million tonnes previously forecast, the company said.

Profit, however, will still be higher than the $39.6 million reported a year earlier.

"On site management had done a good job in managing productivity and stockpiles to the end of November in difficult conditions, however the continuing unseasonal wet weather has meant that productivity and coal availability has been significantly affected in December," Macarthur said.

The Australian dollar is stronger than previously forecast, the company added.

Shares in Macarthur Coal fell 37 cents, or 2.94 per cent, at $12.22 at 1245 AEDT.