Best time to fly Boston to Los Angeles

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

Best month

May

85.2% on time · 834 flights

Worst month

February

64.7% on time · 637 flights

Month Flights On time Cancelled When late, by
January 693 77.6% 3.03% 79 min
February 637 64.7% 4.71% 79 min
March 746 83.7% 0.54% 83 min
April 725 80.5% 0.14% 69 min
May 834 85.2% 0% 69 min
June 846 74.1% 0.47% 67 min
July 869 73.2% 1.04% 81 min
August 900 80.5% 0.33% 70 min
September 803 82.1% 0% 94 min
October 889 79.4% 0.34% 101 min
November 767 80.9% 0.65% 86 min
December 753 70.1% 0.66% 77 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.