Best time to fly London to Glasgow

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

Best month

February

90.5% on time · 1,176 flights

Worst month

September

61.8% on time · 566 flights

Month Flights On time Cancelled When late, by
January 1,313 80.6% 3.27% 0 min
February 1,176 90.5% 0.17% 0 min
March 1,321 86.1% 2.04% 0 min
April 1,153 85.8% 0% 0 min
May 1,168 77.2% 0.86% 0 min
June 1,054 72.4% 1.04% 0 min
July 534 67.5% 2.62% 0 min
August 550 76.5% 0.36% 0 min
September 566 61.8% 1.41% 0 min
October 626 73.9% 1.6% 0 min
November 635 86.5% 0% 0 min
December 652 81% 1.53% 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.