The North Dakota Industrial Commission said oil production in October, the last full month for which statistics are available, was 941,637 barrels per day, an all-time high for the state.
Commission Director Lynn Helms said in his monthly report all of the roads in McKenzie county, which accounts for 29 percent of the state's oil production, were closed for several days in October because of heavy rains.
"This means production likely would have been 10,000-15,000 barrels per day higher without that weather event," he said in his report, published Friday.
Helms said more than 95 percent of the drilling activity in the state targets the Bakken and Three Forks formations, two of North Dakota's most promising oil fields.
The U.S. Energy Information Administration, the Energy Department's analytical arm, recently estimated oil production from the Bakken reserve area would top 1 million bpd in December.
Bakken, spread out over western North Dakota, accounts for about 10 percent of total U.S. oil production, the EIA said.