Best time to fly Chicago to Oakland

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

There is not yet enough of the year on record for this route to say anything about seasons. The months below are shown as recorded.

Month Flights On time Cancelled When late, by
January 32 75% 0% 65 min
February 28 71.4% 0% 72 min
March 54 64% 7.41% 53 min
April 53 56.6% 0% 57 min
May 52 73.1% 0% 44 min
June 56 53.6% 0% 54 min
July 35 58.8% 0% 58 min
August 37 78.4% 0% 37 min
September 34 76.5% 0% 27 min
October 35 45.7% 0% 33 min
November 33 67.7% 6.06% 65 min
December 33 36.4% 0% 44 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.