Best time to fly Chicago to Manchester

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

Best month

April

85.9% on time · 72 flights

Worst month

July

78.6% on time · 135 flights

Month Flights On time Cancelled When late, by
April 72 85.9% 1.39% 44 min
May 147 81.9% 0.68% 61 min
June 162 83.4% 3.09% 53 min
July 135 78.6% 2.22% 66 min
August 141 80.6% 1.42% 53 min
September 145 82.8% 0% 50 min
October 136 82.4% 0% 42 min
November 6 83.3% 0% 66 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.