Best time to fly Chicago to New York

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

Best month

January

83.6% on time · 398 flights

Worst month

June

61.1% on time · 402 flights

Month Flights On time Cancelled When late, by
January 398 83.6% 3.52% 41 min
February 365 82.6% 3.84% 58 min
March 391 63.3% 6.39% 65 min
April 386 75.7% 0.52% 53 min
May 396 71.1% 1.52% 64 min
June 402 61.1% 3.48% 60 min
July 416 69.1% 3.61% 74 min
August 407 70.5% 3.93% 58 min
September 400 82.8% 0.5% 39 min
October 405 75.1% 1.23% 47 min
November 383 78.4% 3.13% 69 min
December 396 67.8% 2.02% 60 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.