The place is great in summer as well in winter. In the warm month you might expect 100+ dogs here on busy times during the day. Winters are not crowded. You will need a DFA (Chicago Dog Friendly Area) tag which costs a fee of $5 (per season which equals one year Jan-Dec) and you get it only from certain veterinarians. Details can be found on the official MONDOG Organizations website, see below.
Since there's no day pass available visitors cannnot go to the park w/o risking a ticket. But check the MONDOG website for any news and changes.
Address: The area between W Lawrence Ave & W Wilson Ave & N Simonds Dr, Chicago
This is in the 'Uptown' neighborhood right north of Lincoln Park.
More informtion regarding Dog Friendly Areas in Chicago can be found on the website of the Chicago Park District, see below. They also have an updated list with participating vets for the 'tag' program.