KMDW — Chicago Midway International Airport
fog forecast & climatology · Chicago city page · full 10-year analysis →
No fog signal in NWS guidance for the next 48 hours. September typically brings about 1 hour of dense fog here.forecast cycle 2026-09-04T13:00:00Z · page rebuilt daily · live layers below update hourly
- Fog hours per year
- 13 h below CAT I minima (2016–2026 average)
- Fog season
- January and February
- Typical fog event
- ~1 h once it forms (middle half 1–3 h, n=70)
- Data through
- 2026-08-15 · machine-readable data.json
When this airport fogs in
In a typical year Chicago Midway International Airport spends 13 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in January and February. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.
Fog season
Fog season runs December through February, peaking in January; fog is mostly a 3 AM–7 AM phenomenon; typically thinning out by 8 AM; a typical event lasts about 1 hour once it forms local time · 10-yr average
Runway infrastructure
| end | approach lights | best approach | length | RVR |
|---|---|---|---|---|
| 04L | — | — | 5,507 ft | — |
| 22R | — | LPV | 5,507 ft | — |
| 04R | — | CAT I | 6,445 ft | RVR |
| 22L | — | — | 6,445 ft | RVR |
| 13L | RLLS | CAT I | 6,522 ft | RVR |
| 31R | RLLS | CAT I | 6,522 ft | RVR |
| 13R | — | — | 3,859 ft | — |
| 31L | — | — | 3,859 ft | — |
From FAA NASR / curated AIP Canada research. Approach-light class and minima tier drive how low an approach can be flown — details in the chase board.
For flight operations
EFVS crews: the CHASE board ranks airports by live fog status, approach lighting, go-around height and flight time from your base. Forecast probabilities publish here per-airport once the calibrated model beats climatology on live verification — receipts on the scorecard. Methodology.
Sources: NOAA/NWS National Blend of Models guidance · METAR observations 2016–2026 (Iowa Environmental Mesonet) · FAA NASR. Machine access: data.json · llms.txt. Not for operational use.