Best time to fly Buffalo to Chicago

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

Best month

May

83.6% on time · 447 flights

Worst month

December

66.1% on time · 324 flights

Month Flights On time Cancelled When late, by
January 287 67.2% 3.14% 73 min
February 249 73.4% 1.61% 95 min
March 330 73.3% 3.33% 85 min
April 388 80.6% 3.09% 63 min
May 447 83.6% 0.22% 97 min
June 398 80.1% 4.02% 78 min
July 389 71.1% 1.29% 99 min
August 348 69.8% 1.72% 80 min
September 339 79.9% 0.29% 111 min
October 343 81.3% 0% 42 min
November 332 77.6% 3.31% 87 min
December 324 66.1% 2.47% 92 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.