How often does weather delay flights at Chambéry-Aix-les-Bains?
From January 2018 to September 2026, EUROCONTROL recorded arrival restrictions for weather (regulation reason W) at Chambéry-Aix-les-Bains (CMF) on 47 of 3,145 days (1.5%). The worst month is December: 6% of days and 1.9 minutes of weather delay per arriving flight on average. Calmest: May–November (0% of days). Weather caused 53% of all arrival-regulation delay minutes at this airport. Source: EUROCONTROL.
Month by month
| Month | Days with weather restrictions | Days with ≥ 1 min per arrival | Minutes per arriving flight |
|---|---|---|---|
| January | 4% | 3% | 0.99 |
| February | 4% | 4% | 0.87 |
| March | 3% | 3% | 0.63 |
| April | 1% | 1% | 0.43 |
| May | 0% | 0% | 0.00 |
| June | 0% | 0% | 0.00 |
| July | 0% | 0% | 0.00 |
| August | 0% | 0% | 0.00 |
| September | 0% | 0% | 0.00 |
| October | 0% | 0% | 0.00 |
| November | 0% | 0% | 0.00 |
| December | 6% | 4% | 1.91 |
Share of days on which EUROCONTROL's network manager limited arrivals because of weather at or around the airport (regulation reason W), 2018–2026. Minutes per arriving flight = weather-regulation delay ÷ all arrivals that month. Worst weeks of the year: week 52 (12%), week 1 (10%), week 8 (8%).
Year by year
| Year | Days with weather restrictions | Minutes per arriving flight | Arrivals |
|---|---|---|---|
| 2018 | 4 of 359 | 0.56 | 3,510 |
| 2019 | 1 of 363 | 0.18 | 3,667 |
| 2020 | 2 of 334 | 1.09 | 2,644 |
| 2021 | 1 of 363 | 0.08 | 2,042 |
| 2022 | 10 of 365 | 0.83 | 3,827 |
| 2023 | 6 of 363 | 1.01 | 3,674 |
| 2024 | 9 of 365 | 1.05 | 3,789 |
| 2025 | 9 of 363 | 0.79 | 3,997 |
| 2026 (Jan–Sep) | 5 of 270 | 0.71 | 3,029 |
2020–2021: far fewer flights during the pandemic.
Weather among all causes
| Cause of arrival regulation | Share of delay minutes |
|---|---|
| Weather | 53% |
| Aerodrome capacity | 26% |
| Industrial action (atc) | 11% |
| Air traffic control capacity | 8% |
Causes with at least 2% of all arrival-regulation delay minutes, 2018–2026.
What the weather was like on those days
| In the airport's weather reports (METAR, 05–21 UTC) | Days with weather restrictions | Other days | Ratio |
|---|---|---|---|
| Thunderstorm reported | 0.0% | 8.7% | — |
| Fog or visibility under 800 m | 28% | 5.0% | 5.5× |
| Cloud base at or below 200 ft | 6.4% | 0.6% | — |
| Gusts of 30 knots or more | 6.4% | 3.3% | 1.9× |
| Crosswind of 20 knots or more on the best runway | 0.0% | 0.1% | — |
| Snow | 13% | 2.9% | 4.4× |
| Freezing rain or drizzle | 2.1% | 0.1% | — |
On 57% of the restriction days none of these showed up in the airport's own reports: restrictions are also set on forecasts, for weather on the approach or elsewhere in the area, and when the wind direction forces a less efficient runway layout. The weather is what came with the delays, not proof of their cause. Based on 3,130 days with full METAR coverage.
The heaviest days
| Date and reported weather | Weather delay, minutes | Arrivals | Minutes per arrival |
|---|---|---|---|
| 30 December 2023 Fog or visibility under 800 m; Cloud base at or below 200 ft | 2,755 | 27 | 102.0 |
| 29 December 2024 Fog or visibility under 800 m; Cloud base at or below 200 ft | 2,106 | 25 | 84.2 |
| 4 January 2020 Fog or visibility under 800 m | 1,886 | 41 | 46.0 |
| 24 February 2018 none of these in the airport's METAR | 1,447 | 50 | 28.9 |
| 26 February 2022 none of these in the airport's METAR | 1,039 | 52 | 20.0 |
What these numbers cover
- Only delays from air traffic flow management (ATFM) regulations on arrivals are counted — not all delays, not departures, and not cancellations or diversions. A day with restrictions does not mean every flight was late.
- Airport ICAO code LFLB, IATA CMF. Ranking by share of restriction days: 60 of 94 airports on this site.