Best time to fly Chicago to Marquette

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

Best month

August

86.7% on time · 85 flights

Worst month

January

55.9% on time · 36 flights

Month Flights On time Cancelled When late, by
January 36 55.9% 2.78% 123 min
February 45 61.4% 2.22% 154 min
March 62 64.7% 14.52% 108 min
April 76 75.7% 6.58% 74 min
May 76 82.7% 1.32% 119 min
June 60 75% 3.33% 48 min
July 61 62.3% 0% 76 min
August 85 86.7% 2.35% 32 min
September 62 80.6% 0% 175 min
October 61 72.1% 0% 56 min
November 59 85.5% 6.78% 250 min
December 60 56.9% 13.33% 87 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.