Best time to fly Detroit to Chicago

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

Best month

September

80.8% on time · 481 flights

Worst month

December

55% on time · 420 flights

Month Flights On time Cancelled When late, by
January 407 58.9% 2.95% 100 min
February 443 75.2% 0% 82 min
March 488 59.8% 5.94% 106 min
April 568 76.6% 3.7% 109 min
May 600 79.6% 1.83% 79 min
June 524 79.2% 4.77% 85 min
July 536 67.7% 2.24% 90 min
August 501 75.5% 2.79% 61 min
September 481 80.8% 0.42% 61 min
October 519 75.7% 0% 67 min
November 472 71.6% 8.26% 87 min
December 420 55% 3.57% 118 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.