Local Aviation Climatology

This Local Aviation Climatology provides information regarding the five airports for which WFO Chicago writes a Terminal Area Forecast (TAF). Please select the desired airport site and climatology product (wind rose or flight category histogram) from the lists below.

Site Product
climatology image

Wind Rose Description: The wind roses show the prevailing wind during a given month for each airport.  Wind roses like these can be calculated for certain periods of the day, but these graphics represent a 24-hour average.  The length of each spoke indicates the percentage of time the wind is from a certain direction. The color-shading indicates what percentage of time the wind speed is from that direction.

Histogram Description: The histograms show the percentage of time that each airport experiences MVFR or lower flying conditions (per month and annually) based on visibility, ceiling, or both ceiling and visibility restrictions. Below is a table of the specific flight categories.

Flight Rules Ceiling Visibility
VFR > 3,000 feet > 5 SM
MVFR 1,000-3,000 feet 3-5 SM
IFR 500-999 feet ≥ 1 SM & < 3 SM
LIFR 200-499 feet ≥ 1/2 SM & < 1 SM
VLIFR ≤ 199 feet < 1/2 SM

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