KTVF — Thief River Falls Regional Airport
fog forecast & climatology · Thief River Falls city page · full 10-year analysis →
Fog unlikely through Saturday (peak 5%). September typically brings about 4 hours of dense fog here.forecast cycle 2026-09-04T13:00:00Z · page rebuilt daily · live layers below update hourly
- Fog hours per year
- 89 h below CAT I minima (2016–2026 average)
- Fog season
- January and March
- Typical fog event
- ~2 h once it forms (middle half 1–3 h, n=311)
- Data through
- 2026-08-15 · machine-readable data.json
When this airport fogs in
In a typical year Thief River Falls Regional Airport spends 89 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in January and March. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.
Fog season
Fog season is January, February, March, April, August, October, November, December, peaking in January; fog is mostly a 3 AM–9 AM phenomenon; typically thinning out by 1 PM; a typical event lasts about 2 hours once it forms local time · 10-yr average
Runway infrastructure
| end | approach lights | best approach | length | RVR |
|---|---|---|---|---|
| 04 | — | LPV | 4,997 ft | — |
| 22 | — | LPV | 4,997 ft | — |
| 13 | — | LPV | 6,504 ft | — |
| 31 | MALSR | CAT I | 6,504 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.