Best time to fly London to Oslo (Gardermoen)

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

Best month

May

89.2% on time · 195 flights

Worst month

June

80.7% on time · 410 flights

Month Flights On time Cancelled When late, by
January 193 81.3% 0% 0 min
February 173 89% 0% 0 min
March 219 86.7% 3.65% 0 min
April 199 86.7% 1.51% 0 min
May 195 89.2% 0% 0 min
June 410 80.7% 2.68% 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.