Best time to fly San Francisco to Pasco/Kennewick/Richland

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

Best month

March

89.1% on time · 93 flights

Worst month

May

67.6% on time · 102 flights

Month Flights On time Cancelled When late, by
January 111 87.3% 0% 89 min
February 101 82.8% 1.98% 85 min
March 93 89.1% 1.08% 59 min
April 89 75.3% 0% 64 min
May 102 67.6% 0% 72 min
June 117 71.8% 0% 139 min
July 92 75% 0% 47 min
August 86 83.7% 0% 49 min
September 108 79.6% 0% 74 min
October 124 79% 0% 49 min
November 118 85.3% 0.85% 41 min
December 122 84.2% 0.82% 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.