Best time to fly San Francisco to Las Vegas

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

Best month

January

79.7% on time · 1,045 flights

Worst month

June

70.3% on time · 1,011 flights

Month Flights On time Cancelled When late, by
January 1,045 79.7% 0.1% 66 min
February 911 79.3% 0.33% 67 min
March 1,021 79.6% 0.49% 60 min
April 1,002 72% 0.4% 56 min
May 1,054 70.4% 0.28% 67 min
June 1,011 70.3% 0.89% 70 min
July 941 72.8% 2.13% 69 min
August 1,013 78.5% 0.49% 61 min
September 1,049 75% 0.57% 69 min
October 1,096 74.7% 0.46% 62 min
November 1,041 75% 1.15% 62 min
December 1,043 76.3% 0.48% 55 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.