June through September in the Chicago area can be very warm and humid with temperatures between 20 and 40°C. From October through April the weather turns gradually colder, averaging about 0°C; periodically, temperatures are as low as -10 to -20°C. Boots are important as the Chicago area can have snow on the ground ranging from a few inches to one or two feet!
You will need warm winter clothing:
- Insulated coat(s) and jacket(s)
- Warm boots, snow boots
- Warm coat/or insulated jacket
- Thermal innerwear