<p>I agree it can be warm into early October. My grown kids wear shorts until the snow flakes start and even then the shorts are on until the snow sticks (not with flip flops though). Me, I put the shorts away from it gets into the mid 60s. It’s generally safe to assume shorts until late September, mixed bag in October and pants until spring for crossing campus.</p>
<p>She can wear shorts for about half the days in September, for about two warm spells (3-4 days apiece) in October, and possibly a couple of days in November. However, in October and November, the weather in mornings and evenings won’t be appropriate for shorts, so she’ll get little wear out of them overall, and will get much more wear from medium weight long pants.</p>
<p>I find this an amusing topic. My S attends Northwestern, and a guy he knows will be attending come September. We’re all from SoCal. His friend was pretty notorious for not wearing long pants until his mother insisted, for events like weddings or funerals. Now the betting is on regarding how long his friend will last in Evanston, next to the lake, before he breaks down and wears the long pants. If the guy owns more than one pair, I’d be surprised.</p>
<p>The marathon wasn’t called off, but they did close the course and kept a lot of the slower runners from continuing.</p>
<p>Chicago weather varies greatly day to day. I’d say the general day the temps start falling is September 27th, with a window of about 20 days. Keep in mind, however, that sometimes there are weeks of cold weather, followed by warm weather, and back to freezing. In fact, this past June, The temperature changed from being 97 to 60 in a 24 hour period. So pack varied types of clothing for sure!</p>
<p>Most of September is typically shorts weather, and then it’s cooler/fall-like in October, but I wouldn’t pack away the shorts at the end of September. Last October, it was unseasonably warm in early October; we visited Chicago in mid October 2007 and it was in the 90’s (I think this was the weekend of the marathon referred to above). I’ve also visited at the end of October and had to purchase gloves/scarves because it was so cold.</p>