Best time to fly Newark to Chicago

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

Best month

September

80.2% on time · 1,021 flights

Worst month

July

62.4% on time · 1,036 flights

Month Flights On time Cancelled When late, by
January 980 75.3% 3.27% 64 min
February 910 74.6% 3.41% 60 min
March 1,041 72% 2.98% 86 min
April 1,033 74.6% 2.23% 84 min
May 1,066 73.7% 3.19% 81 min
June 1,001 72.9% 1.8% 95 min
July 1,036 62.4% 5.79% 104 min
August 1,039 67.9% 3.46% 91 min
September 1,021 80.2% 0.78% 69 min
October 1,090 71.5% 0.37% 53 min
November 1,074 68.2% 2.89% 67 min
December 1,056 69.2% 0.95% 71 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.