Best time to fly London to Los Angeles

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

Best month

April

81.6% on time · 270 flights

Worst month

March

71.8% on time · 259 flights

Month Flights On time Cancelled When late, by
January 226 71.9% 0.88% 0 min
February 199 81.2% 1.01% 0 min
March 259 71.8% 5.41% 0 min
April 270 81.6% 1.11% 0 min
May 281 77.2% 1.78% 0 min
June 544 80% 1.65% 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.