Best time to fly Chicago to Newark

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

Best month

May

81.5% on time · 552 flights

Worst month

July

54.1% on time · 498 flights

Month Flights On time Cancelled When late, by
January 479 73.9% 5.64% 67 min
February 440 74.3% 7.27% 59 min
March 510 70% 4.71% 82 min
April 535 78.4% 1.5% 70 min
May 552 81.5% 0.91% 92 min
June 529 70.7% 2.65% 85 min
July 498 54.1% 6.63% 106 min
August 493 63.2% 1.22% 85 min
September 473 72.5% 1.48% 84 min
October 502 62.9% 0.4% 72 min
November 521 68.4% 5.76% 111 min
December 512 62% 1.76% 69 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.