How reliable is George Bush Intercontinental Houston Airport?
Flights from IAH departed within 15 minutes of schedule in 80% of 974,410 flights in official BTS history — and weather is calmest in Aug. 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 IAH looks like
On-time departures
across 974,410 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 Houston
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 · 98/100 favorability
Roughest month
Most disruptive — low visibility & fog, thunderstorms · 87/100 favorability
Connecting through IAH
How much layover you really need
Based on 158 sellable domestic itineraries seen through Google Flights. Median observed layover: 95 min.
International transfers add immigration and bag recheck — give yourself this buffer at IAH 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 IAH
What the numbers say about flying through George Bush Intercontinental Houston Airport
Across official performance history, flights from Houston left within 15 minutes of schedule about 80% of the time over 974,410 flights. That's a solid, better-than-average operational record. Pair it with a moderate cancellation rate of 1.7%. When a departure does run late, the typical delay is around 14 minutes.
On weather, Houston is an unusually calm-weather airport year-round. August is the calmest stretch for flying, scoring 98 out of 100 for favorable conditions, while December is the most disruptive at 87, driven mainly by low visibility & fog and thunderstorms. The year is relatively steady, so no single month stands out as one to avoid on weather alone.
If you're connecting through IAH, give yourself room. Real itineraries sold through IAH bottom out around 67 minutes for a domestic connection, and international transfer wants roughly 95 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 Houston, 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 IAH
- How reliable is George Bush Intercontinental Houston Airport (IAH)?
- Flights from Houston left within 15 minutes of schedule roughly 80% of the time across 974,410 flights of official history — a solid, better-than-average operational record. The cancellation rate runs about 1.7%. It's advisory context, not a guarantee for any single flight.
- What is the best month to fly from IAH for good weather?
- August has the calmest flying weather at George Bush Intercontinental Houston Airport. December is the most disruptive, mainly from low visibility & fog and thunderstorms.
- How much layover time do you need at IAH?
- Allow at least about 67 minutes for a domestic connection and about 95 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 Houston?
Score real flights to and from IAH on reliability, weather, and connection safety — not just price.