Best time to fly London to Miami

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

Best month

April

82.2% on time · 320 flights

Worst month

January

68.7% on time · 331 flights

Month Flights On time Cancelled When late, by
January 331 68.7% 0.6% 0 min
February 324 79.7% 1.23% 0 min
March 352 74.8% 3.13% 0 min
April 320 82.2% 1.56% 0 min
May 325 79.5% 2.46% 0 min
June 288 69.9% 6.6% 0 min
July 156 72.5% 1.92% 0 min
August 154 81.6% 1.3% 0 min
September 149 74.8% 1.34% 0 min
October 156 76.9% 0% 0 min
November 156 76.5% 1.92% 0 min
December 167 70.1% 1.8% 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.