Third fourth or fifth the handwarmer/footwarmer idea. Any outdoor clothing/gear shop will have them. If you have a Sorrel type boot (like this: http://www.sorel.com/mens-bear-xt-boot-1573911.html?cgid=men&dwvar_1573911_variationColor=010#start=14 ) wear them! Make sure that you watch out for black ice - it’s been really treacherous here the last couple of days.
If you don’t have long underwear tights under pants are almost as effective.
Toured Northwestern this past Saturday. it was positively balmy - 41 and sunny!
I know people say to wear layers but IMO it’s easier to have one big thing to put on or take off, rather than 5, in a tour/info session situation.
I appreciate the question OP! S is about to do just what you describe. We have lived in cold environments, but not in a long time, so we needed the memory jog.
Also laughing at the jacket-optional-above-15 thing, lol. I’m in central PA and it’s been in the single digits for a while; it finally got back up to the 30s this week and lots of the kids were walking around in sweatshirts and thick sweaters (although just as many were in North Face coats). I personally wear a lighter-weight poly-fill jacket in the 30s. 20s and teens honestly isn’t that cold if you keep it moving outside - I have a big down coat with earmuffs and scarf and I feel hot at my core after about 20 minutes of activity in the teens with that coat on. I’d only do the long underwear if you anticipate being outside for a long time - a one-hour tour shouldn’t necessitate long johns, lol.
Old myth. See [url=http://www.livescience.com/34411-body-heat-loss-head.html]here[/url]. You lose no more body heat through your head than you do through any other exposed part of your body. I have an afro so I never wear a hat outside unless my hair is braided and my scalp’s exposed. One, because I have so much hair that I don’t feel anything through my hair anyway, and two, because of vanity - the hat would crush the afro down lol. I wear earmuffs instead!
The worst tours were when the weather the day before was nice! 40 and rain at Purdue, miserable! It was 65 the day before and I didn’t bring enough clothes.
The only tour we bailed on was at Case Western when it was snowing sideways on spring break. Our first stop of the week was 70 and sunny.
I have hand and toe warmers in my glove box in case I’m really cold. Like someone said above, you can find them for a $1, they are cheap and easy. Have a coat that covers your bottom, it makes it much warmer. Wool socks are nice when it’s wet or cold out, I think the wool helps repel water. Definitely a hat and gloves.
My tip, even if it looks like the weather is going to be nice, pack for wet and cold. Be prepared for anything.
“Old myth. See here. You lose no more body heat through your head than you do through any other exposed part of your body.”
I’d wear / bring ear muffs, though. Of course you’ll have to weigh that against not hearing what the guide has to say!
Honestly, the cold won’t be a big deal at all if it’s sunny.
OK, let’s try it another way.
After living in the midwest for 30 years, I have discovered that I feel much more comfortable in cold weather when my head is covered up with a cozy hat. Over the centuries others have come to the same conclusion and have made or purchased hats out of animal hides, fur, wool and other materials.
There are some colleges with underground tunnels (U. Rochester has them) so no surprise about t-shirts and flip flops!
BU doesn’t have tunnels, and it’s cold. Still, plenty of flip flops and pajama pants…even in the dead of winter!
One of D’s friends is from Georgia and is going to NU next year. His mom wants to make sure the weather will be bearable, so they’re visiting next month to make sure winters won’t be too harsh.
Of course when you grow up in the Midwest, you have a different temperature gauge. We went prom dress shopping on Saturday and neither my daughter nor her friend opted to wear coats because it was “too warm for a jacket” at about 40°F. 
Carry a tote or a backpack that you can use either to hold warm weather gear in case you need it…or to stow it if you need to take it off because you are too warm.
I think the Northeast/Midwest divide, where supposedly the Midwest is soooo much colder, is a bunch of nonsense. My D in Boston has had worse weather than her twin in Chicago these last 4 years. We just get the cold fronts a day before she does, that’s all.
YMMV. In my experience, the Northeast’s oh-so-bad weather was overexaggerated, and my Midwestern home state was consistently colder and snowier (which I rather like). It’s all in the eye of the beholder.
Many of us in New England think this winter and last have been rather mild. A few low days, a string of low nights but barely snow. Maybe it’s different in VT, probably in parts of NY.
I personally hate walking in cold weather. My sinuses start hurting and if I walk enough to get the blood pumping, I start getting hives on my legs. Ugh. Shovelling my driveway can be torture, LOL.
To the OP, I second the suggestion of hand & foot warmers, as well as a hat & scarf, layers, and good boots. Since cold wind also makes my contacts dry up, I also usually wear sunglasses as windshields.
Good luck.
"Of course when you grow up in the Midwest, you have a different temperature gauge. We went prom dress shopping on Saturday and neither my daughter nor her friend opted to wear coats because it was “too warm for a jacket” at about 40°F. "
I’d wear a coat if I were walking around outside at 40 degrees, but honestly, right now when I’m mostly going from my garage to my work parking garage or maybe running a very quick errand, 40 degrees doesn’t remotely require a coat - as long as one is in the backseat just in case!
It is nonsense. The midwest has on average something like 20 more sunny days a year than the northeast. Because the winters are slightly colder, there’s less of that awful ice that causes such treacherous driving. There is actually less snow than people seem to think. Just looking at MN vs. MA, MN has 43 inches of snow per year on average while MA has 51.
Both “Northeast” and “Midwest” are big regions with diverse weather. North Dakota is of course much colder than Connecticut, almost every year. On the other hand, Maine is almost always much colder than southern Indiana. Just plan for the weather where you will be, and have layers available. Remember “The coldest winter I ever spent was a summer in San Francisco.”
Haha…so true about San Francisco.
I don’t think of North Dakota as the Midwest, but you are right that both the Northeast and Midwest are big regions.
I think some of us bristle when this conversation comes up because we see so many posts about people who don’t want their kids to go to college in, say, Chicago or the Twin Cities “because of the weather” but they’d happily send them to a school in Boston or New York.
My problem recently touring schools in Indiana was more related to overheating indoors rather than keeping warm outside. It was cold and windy, so I had a jacket, gloves, hat, warm socks and hiking shoes. I was fine outside. However, I’m at an age where i overheat rapidly 
and found myself stripping off the hat, gloves, and jacket every time we walked in to a building, only to have to put them on again when we were ready to walk outside. So my recommendation is to wear a coat you can get on/off quickly…