Best time to fly Salt Lake City to Boston

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

Best month

May

92.4% on time · 93 flights

Worst month

October

75% on time · 92 flights

Month Flights On time Cancelled When late, by
January 92 83.5% 7.61% 58 min
February 110 81.2% 8.18% 64 min
March 132 80.3% 0% 52 min
April 92 81.3% 0% 48 min
May 93 92.4% 1.08% 74 min
June 110 83.6% 0% 54 min
July 123 76.9% 1.63% 62 min
August 116 85.2% 0.86% 62 min
September 92 78.3% 0% 68 min
October 92 75% 0% 70 min
November 97 88.7% 0% 50 min
December 107 81% 1.87% 74 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.