Best time to fly Indianapolis to Seattle

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

Best month

October

90.1% on time · 94 flights

Worst month

June

64.4% on time · 120 flights

Month Flights On time Cancelled When late, by
January 58 70.9% 5.17% 54 min
February 50 72% 0% 54 min
March 69 66.2% 1.45% 47 min
April 89 83% 1.12% 46 min
May 124 82.9% 0.81% 35 min
June 120 64.4% 1.67% 59 min
July 123 74.4% 0.81% 68 min
August 120 66.7% 0% 59 min
September 106 72.6% 0% 38 min
October 94 90.1% 3.19% 38 min
November 76 81.6% 0% 34 min
December 86 72.9% 1.16% 55 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.