Best time to fly Houston to Salt Lake City

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

Best month

September

87.7% on time · 334 flights

Worst month

July

69.4% on time · 306 flights

Month Flights On time Cancelled When late, by
January 371 85.6% 2.16% 68 min
February 349 85.9% 0% 69 min
March 417 85.2% 0.96% 114 min
April 320 81.8% 0% 59 min
May 298 78.1% 0.34% 77 min
June 292 76.2% 0.68% 71 min
July 306 69.4% 3.92% 102 min
August 320 80.4% 0.63% 69 min
September 334 87.7% 0% 63 min
October 316 86.3% 0% 63 min
November 273 83.2% 0% 85 min
December 357 80.5% 0.56% 91 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.