Best time to fly Prague to London

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

Best month

March

89.6% on time · 293 flights

Worst month

September

63.8% on time · 142 flights

Month Flights On time Cancelled When late, by
January 272 76.6% 1.1% 0 min
February 257 87% 1.56% 0 min
March 293 89.6% 1.71% 0 min
April 299 87.9% 0.67% 0 min
May 291 84.4% 0.69% 0 min
June 274 73.8% 1.09% 0 min
July 151 74.3% 1.99% 0 min
August 150 84.7% 0% 0 min
September 142 63.8% 0.7% 0 min
October 154 81% 0.65% 0 min
November 143 85.9% 0.7% 0 min
December 154 77.1% 0.65% 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.