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 |
|---|
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 |
