NEW YORK, Jan 29 (Reuters) - Less than 5% of North Dakota's oil output remained shut in due to extreme cold weather and operational challenges, the state's pipeline authority said on Monday.

Oil output in the third largest oil producing state was estimated to be down 10,000 barrels per day (bpd) to 40,000 bpd, according to the North Dakota Pipeline Authority. That level compares to over 50% lost output earlier this month. (Reporting by Stephanie Kelly)