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

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

Best month

March

88.3% on time · 137 flights

Worst month

June

70% on time · 302 flights

Month Flights On time Cancelled When late, by
January 119 74.1% 2.52% 0 min
February 117 82.9% 0% 0 min
March 137 88.3% 0% 0 min
April 130 82.9% 0.77% 0 min
May 142 75.2% 0.7% 0 min
June 302 70% 0.66% 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.