Southeast Wisconsin in December

May through October gives you Southeast Wisconsin at its best. Late spring brings wildflowers and fewer crowds, though lake temperatures stay chilly until July. Summer means festival season - Summerfest in Milwaukee runs late June through early July and draws nearly a million people. Book accommodations months ahead. Fall colors peak in early October, especially around Lake Geneva and the Kettle Moraine State Forest. September offers the sweet spot - warm days, cool nights, and summer crowds gone home. Plus, Oktoberfest celebrations run all month in Milwaukee's German neighborhoods. Winter is harsh but beautiful if you're into it. Wisconsin Dells transforms into a winter sports destination, and Milwaukee's indoor attractions shine. Just pack serious cold weather gear - temperatures regularly drop below zero, and lake-effect snow can strand you unexpectedly. Avoid major summer weekends in Lake Geneva unless you enjoy traffic jams and inflated prices. Wisconsin Dells gets absolutely mobbed from Memorial Day through Labor Day - go early May or after school starts for sanity.