Best time to fly Washington to Houston

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

Best month

February

89.7% on time · 258 flights

Worst month

May

70.9% on time · 288 flights

Month Flights On time Cancelled When late, by
January 282 84.1% 6.38% 64 min
February 258 89.7% 2.33% 59 min
March 289 83% 3.81% 149 min
April 282 83.3% 0% 84 min
May 288 70.9% 1.04% 67 min
June 280 71.9% 2.86% 95 min
July 207 74.6% 2.42% 153 min
August 207 82.8% 0.97% 72 min
September 272 86% 0% 53 min
October 291 87.6% 0% 42 min
November 270 81.3% 2.96% 66 min
December 274 80.5% 0.73% 73 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.