Best time to fly Williston to Denver

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

Best month

October

88% on time · 244 flights

Worst month

July

68.7% on time · 255 flights

Month Flights On time Cancelled When late, by
January 207 71.1% 4.35% 88 min
February 199 73% 1.51% 106 min
March 233 74.9% 1.29% 86 min
April 203 71.9% 0.49% 139 min
May 245 78.3% 0.82% 92 min
June 261 71.1% 0.77% 92 min
July 255 68.7% 0.78% 100 min
August 256 77.2% 0.78% 110 min
September 249 86.7% 0% 68 min
October 244 88% 0.82% 95 min
November 221 73.9% 4.07% 122 min
December 230 69.2% 0.87% 124 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.