Best time to fly Chicago to Anchorage

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

Best month

January

100% on time · 5 flights

Worst month

December

33.3% on time · 15 flights

Month Flights On time Cancelled When late, by
January 5 100% 0%
March 27 61.5% 3.7% 88 min
April 31 58.1% 0% 44 min
May 92 75.8% 1.09% 49 min
June 141 76.3% 0.71% 73 min
July 155 71.4% 0.65% 44 min
August 143 80.3% 0.7% 59 min
September 101 77.2% 0% 40 min
October 47 71.7% 0% 52 min
November 29 71.4% 3.45% 36 min
December 15 33.3% 0% 33 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.