Airports
Best Month to Fly
Some months of the year simply run late. Enter a U.S. airport to see its on-time departure rate for each calendar month — pooled across 2023–2026 of the U.S. DOT's on-time performance filings — so the seasonal pattern shows instead of the folk rule.
Methodology
Every figure is computed directly from the U.S. Department of Transportation's Marketing Carrier On-Time Performance filing (Bureau of Transportation Statistics, table 236), reduced to one row per airport per direction per month. This tool takes an airport's departure rows across every month the site serves (2023–2026) and pools them by calendar month — all Januaries together, all Februaries together, and so on.
- On-time % for a calendar month = departures under 15 minutes late ÷ departures with a filed departure time, summed over every year of that month. The 15-minute threshold is the federal definition of on-time (14 CFR § 234.2), used unchanged.
- Most and least reliable month are the highest and lowest on-time rate among months that clear the sample threshold, and the seasonal swing is their difference in percentage points.
- The year-by-year grid splits each pooled month back into its individual years, so a single anomalous season is visible rather than hidden inside the average. Pooling deliberately uses the full backfill, not a trailing window — seasonality is a month-of-year signal, which needs several years of each month to read.
Scope & limits. U.S. domestic operations of reporting marketing carriers, scored on departures; this tool pools filings from June 2023 through May 2026. Only airports served by reporting carriers appear, and a calendar month with fewer than 30 filed departures over the pool is shown without a rate. With only a few years per month, one severe season can move an average — read the year-by-year grid alongside the headline. These are historical base rates by month, not a prediction for any specific future flight, and they say nothing about which airline you fly.
Last reviewed: July 2026
Frequently asked questions
Is there really a best month to fly?
For punctuality, yes — and it is mostly weather and traffic, not the airline. Summer thunderstorms and winter snow drag on-time rates at most airports, while shoulder-season months tend to run cleaner. This tool shows the actual month-by-month curve for the airport you enter instead of repeating the general rule, because the size and shape of the seasonal swing vary a lot from one field to the next.
How many years is each month averaged over?
The tool pools every year the site currently serves — 2023 to 2026, so each calendar month is the sum of that many separate months of filings. The year-by-year table below the chart breaks the pool back out so you can see whether one unusually bad season is pulling a month's average down, rather than a stable pattern.
What counts as "on time"?
The federal 15-minute rule: a departure is on time if it leaves the gate less than 15 minutes after its scheduled time. Fourteen minutes late still counts as on time; fifteen does not. Every figure here uses that definition unchanged (14 CFR § 234.2), applied to departures because the month you travel is the thing you choose when you book.
Does this predict whether my flight will be late?
No. These are historical base rates by calendar month, not a forecast for any specific date or flight. A month that ran on time 78% of the time over the last few years is a reasonable prior for that season at that airport — but weather in any single year is its own event, and this says nothing about which airline you fly or which day of the month you pick.
Related tools
On-time departure rate by scheduled hour for a U.S. airport — the folk rule to fly early, quantified per airport from the federal record.
Open tool →Airport Delay ProfileDeparture and arrival reliability at a U.S. airport, month by month, with the DOT delay-cause split — carrier, weather, National Aviation System, security, and late-arriving aircraft.
Open tool →Route Reliability CheckOn-time arrival rates, typical and worst-case delays, and cancellations for every airline on a U.S. route — from the DOT's on-time filings.
Open tool →