Best time to fly Boston to Milwaukee

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

Best month

January

93% on time · 62 flights

Worst month

July

75% on time · 169 flights

Month Flights On time Cancelled When late, by
January 62 93% 6.45% 35 min
February 56 90.4% 7.14% 46 min
March 99 86.7% 1.01% 49 min
April 106 90.6% 0% 40 min
May 170 77.5% 0.59% 59 min
June 166 87.7% 1.2% 71 min
July 169 75% 2.96% 87 min
August 175 85.4% 1.71% 58 min
September 152 80.1% 0.66% 66 min
October 161 84.3% 1.24% 47 min
November 100 81.7% 7% 42 min
December 80 81% 1.25% 70 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.