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Know before
you go.

Annual VMC/IMC statistics for any ICAO airport — data-driven VFR planning powered by Iowa Environmental Mesonet.

Ceiling ≥ 1,500 ft Vis. ≥ 5 km (3 SM) Horiz. Sep. ≥ 1,500 m Vert. Sep. ≥ 1,000 ft VMC Day = ≥ 75% obs

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Total days

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VMC Days

Clear sky · Good visibility

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Mixed Days

Variable conditions

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IMC Days

Low clouds · Poor visibility

Monthly VMC / Mixed / IMC distribution

Annual heatmap — each cell = 1 day

Monthly breakdown

Month	VMC	Mixed	IMC	% VMC	Result

Criteria

What are VMC conditions?

Visual Meteorological Conditions (VMC) allow operations under Visual Flight Rules (VFR). For a day to be classified as VMC, at least 75% of its METAR observations must simultaneously satisfy all of the following criteria, per Class E airspace below 10,000 ft.

Cloud ceiling

≥ 1,500 ft AGL. The base of the lowest BKN or OVC cloud layer (or vertical visibility into an obscured sky) must exceed 1,500 feet above aerodrome level.

Visibility

≥ 5 km (3 SM) below 10,000 ft. The prevailing meteorological visibility reported in the METAR must be at least 5 kilometres to allow visual navigation.

Horizontal separation

≥ 1,500 m from clouds. The aircraft must maintain a minimum horizontal distance of 1,500 metres from any cloud to avoid inadvertent IMC entry.

Vertical separation

≥ 1,000 ft from clouds. Both above and below, the aircraft must remain at least 1,000 feet clear of any cloud in the vertical plane.