Best time to fly Tokyo to London

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

Best month

March

89.8% on time · 133 flights

Worst month

February

71.3% on time · 115 flights

Month Flights On time Cancelled When late, by
January 129 88.2% 1.55% 0 min
February 115 71.3% 0% 0 min
March 133 89.8% 3.76% 0 min
April 150 83.9% 0.67% 0 min
May 155 82.6% 0% 0 min
June 299 72.8% 1.67% 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.