Best time to fly Boston to Las Vegas

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

Best month

August

84.9% on time · 106 flights

Worst month

January

69.5% on time · 139 flights

Month Flights On time Cancelled When late, by
January 139 69.5% 5.04% 73 min
February 130 69.7% 6.15% 77 min
March 168 71.4% 0% 64 min
April 165 81.8% 0% 51 min
May 159 74.8% 0.63% 82 min
June 101 72% 0.99% 54 min
July 122 76.3% 1.64% 63 min
August 106 84.9% 0% 51 min
September 146 81.5% 0% 62 min
October 165 72% 0% 80 min
November 116 81.9% 0% 54 min
December 121 72.5% 0.83% 53 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.