Best time to fly Chicago to Spokane

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

Best month

June

80% on time · 60 flights

Worst month

March

29.6% on time · 58 flights

Month Flights On time Cancelled When late, by
January 40 71.8% 0% 61 min
February 43 38.1% 0% 77 min
March 58 29.6% 6.9% 72 min
April 59 66.7% 3.39% 48 min
May 61 59% 0% 55 min
June 60 80% 0% 33 min
July 92 73.9% 0% 74 min
August 79 67.9% 1.27% 65 min
September 72 79.2% 0% 78 min
October 66 69.7% 0% 61 min
November 59 66.7% 3.39% 64 min
December 55 54.7% 0% 135 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.