Best time to fly Denver to Raleigh/Durham

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

Best month

January

86.9% on time · 138 flights

Worst month

July

61.2% on time · 183 flights

Month Flights On time Cancelled When late, by
January 138 86.9% 5.8% 46 min
February 128 82.7% 0.78% 68 min
March 149 77.7% 0.67% 72 min
April 146 78.8% 0% 39 min
May 155 78.6% 0.65% 38 min
June 154 66% 0% 58 min
July 183 61.2% 0% 70 min
August 162 70.4% 1.23% 65 min
September 133 70.7% 0% 38 min
October 136 72.8% 0% 43 min
November 137 82.5% 0% 42 min
December 147 80.3% 0% 63 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.