Boston to San Juan

What the Data Says About BOS to SJU

The Boston to San Juan corridor (BOS → SJU) covers roughly 1,674 miles and is served by 16 carriers, based on Bureau of Transportation Statistics reporting. Across 9,566 flights in the dataset, this route posts a 69.5% on-time rate with an average delay of 73.3 minutes when flights run late. Over the most recent 24 months of BTS data, 3,937 flights were recorded on this pairing — 42 cancelled (1.1%) and 12 diverted (0.3%). Those baseline metrics tell you what to expect before you book.

Having 16 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 9,566 total flights analyzed, the 69.5% on-time figure is statistically meaningful rather than a small-sample fluke. The 73.3-minute average delay applies only to flights that actually ran late, so it is not the average wait across all departures — the majority of flights on this route depart on time under the BTS definition of a delay (15+ minutes past schedule).

Looking at recent months, Sep 2024 posted the best performance on this corridor at 85% on-time, while Dec 2024 came in at 54% on-time — a 31-point gap between best and worst recent month. For travelers evaluating the BOS to SJU route, the combination of a 69.5% on-time rate, 73.3-minute average delay, 1.1% recent cancellation rate, and 16 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.