Best time to fly St. Peter to London

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

Best month

April

92.8% on time · 180 flights

Worst month

January

75.8% on time · 184 flights

Month Flights On time Cancelled When late, by
January 184 75.8% 1.09% 0 min
February 178 91% 0% 0 min
March 190 78% 4.21% 0 min
April 180 92.8% 0% 0 min
May 174 89.1% 0% 0 min
June 346 76.6% 1.16% 0 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.