Best time to fly London to Johannesburg

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

Best month

April

86.7% on time · 90 flights

Worst month

January

64.4% on time · 89 flights

Month Flights On time Cancelled When late, by
January 89 64.4% 2.25% 0 min
February 82 84% 1.22% 0 min
March 93 77.2% 1.08% 0 min
April 90 86.7% 0% 0 min
May 93 75.3% 0% 0 min
June 180 69.5% 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.