Whitehaven CEO Paul Flynn said the company had made progress on improving performance of the bulk materials handling at its operations.

"Across our open cut operations we are seeing much more consistent and better performance across production and overburden management and our guidance range has tightened accordingly," he said.

"During the latter part of the December quarter there was a strong rebound in pricing and we are increasingly optimistic that underlying market dynamics are supportive of continued improvement in this area."

Whitehaven has increased its FY21 managed coal sales - excluding purchased coal - guidance to 19-20Mt, from 18.5-20Mt.

Whitehaven realised an average price of US$62 per tonne for all sales of own thermal coal in the December quarter.

The realised price was 8% lower than the quarterly globalCoal Newcastle Index average due to two main factors: Whitehaven's realised prices lagged the average when rapid changes in the monthly index coal price occurred; and there were increased volumes of other thermal coal sold at fixed prices.

The miner spent A$2.3 million on expansion and growth projects during the December quarter, reflecting approvals and studies relating to the Vickery Extension project, approvals work and land purchase for Narrabri stage three, and environmental studies for Winchester South in Queensland.

"It is pleasing to have reached key milestones for both Narrabri stage three and Winchester South development projects, with the submission of both projects environmental impact statements and Winchester South's maiden reserve statement," Flynn said.

"We are continuing to progress our development pipeline but work is proceeding cautiously and in line with the company's strict capital allocation framework."

The outage of one of Newcastle Coal Infrastructure Group's two ship loaders has resulted in 550,000t of equity sales of own coal slipping from December 2020 into January 2021.

Whitehaven shares closed 3.1% higher at $1.805, the highest since June.