Best time to fly Duluth to Chicago

Every month pooled across the years on record, so "July" means July generally rather than one particular July. Full DLH to ORD record →

Best month

October

87.3% on time · 230 flights

Worst month

January

64.8% on time · 124 flights

Month Flights On time Cancelled When late, by
January 124 64.8% 1.61% 121 min
February 141 74.5% 2.84% 106 min
March 193 65.6% 6.74% 126 min
April 218 70.2% 5.5% 118 min
May 225 78.1% 0.44% 91 min
June 204 66.5% 1.47% 73 min
July 207 75.5% 1.45% 121 min
August 223 70.9% 1.35% 66 min
September 234 83.9% 1.28% 84 min
October 230 87.3% 0% 49 min
November 177 81.8% 3.39% 111 min
December 127 68.3% 5.51% 144 min

What a seasonal pattern can and cannot tell you

Months differ for reasons that repeat — summer thunderstorms in the American interior, winter fog and de-icing in northern Europe, school holidays filling every seat and leaving no slack in the schedule. Those are real and they come back each year.

What the pattern cannot do is forecast a particular flight. A quiet month has late days and a bad month has punctual ones. Treat this as a way to choose between two dates you are indifferent about, not as a promise.