Great Lakes weather is heavily influenced by Lake Michigan. Lake-effect clouds and snow are common October through March on the eastern shore. Summer brings afternoon convective activity, especially inland. Visibility is generally good except during lake-effect events. Wind shear can be significant near the lakeshores. Severe thunderstorms are a summer concern across the entire route.

O'Hare Class B is one of the most complex in the country. The route passes through or near Chicago Class B, Gary/Chicago Class D, South Bend Class C, Kalamazoo Class C, and Detroit Class B for arrival. VFR traffic typically routes south of the O'Hare Bravo through the Gary corridor.

• 1Depart from KDPA or KARR to avoid the ORD Class B entirely
• 2The Gary corridor south of ORD's Bravo is a well-known VFR route
• 3South Bend (KSBN) and Kalamazoo (KAZO) are excellent divert options
• 4Lake-effect clouds can appear rapidly when crossing from west to east
• 5Detroit Class B has lower shelves; plan your altitude carefully
• 6Ann Arbor (KARB) is a good alternative to DTW for GA traffic