Best time to fly Paris (Roissy-en-France to London

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

Best month

February

85.9% on time · 377 flights

Worst month

January

68.7% on time · 413 flights

Month Flights On time Cancelled When late, by
January 413 68.7% 2.42% 0 min
February 377 85.9% 0% 0 min
March 420 82.5% 4.52% 0 min
April 381 83.4% 0.26% 0 min
May 376 82% 0.8% 0 min
June 724 75.1% 2.21% 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.