Best time to fly Hartford to San Juan

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

Best month

May

75.7% on time · 178 flights

Worst month

January

55.9% on time · 182 flights

Month Flights On time Cancelled When late, by
January 182 55.9% 4.95% 78 min
February 157 62% 3.18% 135 min
March 164 57.7% 0% 132 min
April 169 69.3% 0.59% 109 min
May 178 75.7% 0.56% 64 min
June 173 72.3% 0% 101 min
July 181 58.8% 1.1% 84 min
August 184 59.4% 2.17% 119 min
September 111 72.1% 0% 81 min
October 107 65.7% 0.93% 42 min
November 140 66.4% 0% 99 min
December 197 65.5% 1.52% 61 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.