Best time to fly Great Falls to Denver

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

Best month

December

91.9% on time · 124 flights

Worst month

June

72.5% on time · 120 flights

Month Flights On time Cancelled When late, by
January 124 81.3% 0.81% 46 min
February 112 83.8% 0.89% 87 min
March 124 91% 0.81% 98 min
April 120 87.5% 0% 62 min
May 124 82.6% 1.61% 107 min
June 120 72.5% 0% 113 min
July 124 82.2% 3.23% 118 min
August 124 80.3% 1.61% 77 min
September 120 90% 0% 65 min
October 124 89.4% 0.81% 78 min
November 118 86.2% 1.69% 50 min
December 124 91.9% 0% 164 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.