Best time to fly São Paulo to São Luís

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

Best month

February

77.1% on time · 243 flights

Worst month

October

54.5% on time · 11 flights

Month Flights On time Cancelled When late, by
January 248 70.2% 2.42% 36 min
February 243 77.1% 1.23% 42 min
March 253 77% 1.98% 44 min
April 248 71.8% 1.21% 38 min
May 299 70.9% 0% 33 min
June 172 72.2% 1.74% 32 min
July 323 74.5% 0.31% 30 min
October 11 54.5% 0% 23 min
November 124 63.9% 4.03% 38 min
December 146 55.4% 4.79% 53 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.