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 LGW record →

Best month

April

82.6% on time · 124 flights

Worst month

June

57.3% on time · 289 flights

Month Flights On time Cancelled When late, by
January 96 58.3% 0% 0 min
February 115 76.3% 0.87% 0 min
March 134 79.1% 0% 0 min
April 124 82.6% 2.42% 0 min
May 128 74.6% 1.56% 0 min
June 289 57.3% 3.46% 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.