How reliable is Washington Dulles International Airport?
Flights from IAD departed within 15 minutes of schedule in 83% of 492,031 flights in official BTS history — and weather is calmest in Nov. Here’s the full picture before you book.
Reliability score
on-time, cancellations & delays
Weather favorability
year-round climate
Origin-airport operations
What the departure punctuality at IAD looks like
On-time departures
across 492,031 flights
Source: BTS Airport Operations · data through 2026-08-08. Role-specific BTS departure history; advisory context, not a guarantee for any flight.
Weather by month
When the weather works for you at Washington
A calm-weather score (0–100) for each month from decades of airport observations — how often conditions disrupt flying, not temperature. Higher is calmer.
Calmest month
Calmest flying weather of the year · 97/100 favorability
Roughest month
Most disruptive — low visibility & fog, snow · 87/100 favorability
Connecting through IAD
How much layover you really need
Based on 106 sellable domestic itineraries seen through Google Flights. Median observed layover: 58 min.
International transfers add immigration and bag recheck — give yourself this buffer at IAD or more.
Observed windows come from normalized SearchAPI / Google Flights itineraries. They are not official airport MCTs. We score every connecting itinerary against conservative connection floors.
The read on IAD
What the numbers say about flying through Washington Dulles International Airport
Across official performance history, flights from Washington left within 15 minutes of schedule about 83% of the time over 492,031 flights. That's a solid, better-than-average operational record. Pair it with a moderate cancellation rate of 1.6%. When a departure does run late, the typical delay is around 13 minutes.
On weather, Washington is an unusually calm-weather airport year-round. November is the calmest stretch for flying, scoring 97 out of 100 for favorable conditions, while February is the most disruptive at 87, driven mainly by low visibility & fog and snow. The year is relatively steady, so no single month stands out as one to avoid on weather alone.
If you're connecting through IAD, give yourself room. Real itineraries sold through IAD bottom out around 47 minutes for a domestic connection, and international transfer wants roughly 90 minutes once immigration and a bag recheck are in the mix. Those are floors, not comfortable buffers — one inbound delay can erase them, so add margin when the connection matters.
None of this guarantees your specific flight — it’s the backdrop. To turn it into a booking, score real flights to Washington, read how we weigh it all in how the PlaneSane Score works, and brush up with how to pick a reliable flight and avoiding weather delays.
Common questions about IAD
- How reliable is Washington Dulles International Airport (IAD)?
- Flights from Washington left within 15 minutes of schedule roughly 83% of the time across 492,031 flights of official history — a solid, better-than-average operational record. The cancellation rate runs about 1.6%. It's advisory context, not a guarantee for any single flight.
- What is the best month to fly from IAD for good weather?
- November has the calmest flying weather at Washington Dulles International Airport. February is the most disruptive, mainly from low visibility & fog and snow.
- How much layover time do you need at IAD?
- Allow at least about 47 minutes for a domestic connection and about 90 minutes for an international one as a floor. These are minimums, not comfortable buffers — a single inbound delay can wipe them out, so add margin when you can.
Reliability guides
Planning a trip through Washington?
Score real flights to and from IAD on reliability, weather, and connection safety — not just price.