Anything above 15 degrees seems to be “jacket-optional” in the north. Except for during the very cold week we had after Christmas, I have seen people running in shorts and t-shirts nearly every day.
It’s actually good to tour in the lousy weather. This way, your student will see the colleges at their worst, rather than in spring when everything is gorgeous and in bloom. Better to start off with the gray skies and learn to see past that. 
Not sure it’s really needed when you’ll be going in/out of buildings, but if you are going to be out in the cold for an extended time, eg for a sporting event, use a ThermaCare heat wrap. It’ll keep your core toasty for hours!
My kid goes to school in Maine and refused to take a winter jacket to college his entire freshman year. Seemed comfortable in a mid-weight leather jacket and scarf. To me it seems crazy, but then I’m always cold.
We toured Wellesley in an absolute pouring down rainstorm. That’s way worse than cold and sunny IMO.
Are you from a warm climate, I’m assuming?
20s and 10s especially if windy can be uncomfortable if not dressed properly. I would wear long underwear under your slacks and wool socks. We toured over Thanksgiving break and some of the tours on the larger campuses entailed a lot of outside walking.
The above is from another post from the OP. It’s been pretty chilly here in CT. Last winter it was even chillier.
The tour guides will take you in and out of buildings. It’s likely that they will do their talking inside buildings whenever possible. Just wear your warm, outdoor clothing. You should be fine.
Connecticut has pretty nasty weather right now. I can’t imagine where the OP might be going that is much worse.
Last week was pretty cold around NY. I put on my knee length down jacket with a hood, scarf, gloves, winter boots, and I walked 40 city blocks round trip. No problem. I thought OP was from down south or CA.
I’m confused. The poster is from CT? Presumably she has clothing and accessories for winter weather already.
Hat, gloves, scarf, socks and a longer coat if you have one (or tights under jeans) should do it. If there is snow on the ground or it is precipitating, wear boots or some other waterproof footwear. Too much artificial heat from toe warmers and heat wraps would make you very uncomfortable during indoor touring and info sessions. If you were going to an outdoor sporting event or a parade, sure, but to go from building to building it is probably overkill. I really can’t imagine it would be much worse than a really cold day in CT unless there is a severe cold snap. Where are you going?
Thanks for the input all. I don’t make it a habit to walk around outside for long periods in very cold weather, so all very valuable! In November we were up in Canada and it was freezing - we may live in the Northeast but we are not skiers and not originally from this area - and were not used to the cold even with the winter coats, etc., that we had - and that was only in the 30s. Thus, I was wondering how difficult college touring in much colder weather would be.
I’m sure you still have to walk across parking lots to do your shopping, walk the dog, etc. Lots of people in the NE take public transportation, too, and are out there for long periods of time.
Any northerner knows how to layer clothing, wear earmuffs/scarf/gloves, etc. Keep in mind that when you’re walking about your body temp will rise. I can get overheated in my winter coat! I would just say maybe have 2 pairs of gloves and 2 pairs of socks. But honestly teens and 20s shouldn’t be a huge deal for someone who lives in the NE. It’s just part of everyday life in the NE and upper Midwest. It’s not sub-zero or dangerous.
I had to laugh at the “sleeping on the train station floor while backpacking” line! Yes, loooooong gone are those days. Now I sort of complain if the hotel isn’t nice 
So true @thumper1! We toured Northwestern last March and a big snowstorm with gusting winds off of Lake Michigan was hammering campus. It’s not so much the snow, but the biting winds, so a scarf is a good idea. But, yes, we too saw kids in shorts and sneakers with no socks.
Had to laugh about jacket-optional. So true. After a few crisp days, we jokingly call 29 “sweater weather.” Hit 35 and, yup, you just may see some in shorts. But that’s the quick forays- from the car into the market is easy. Or some kid whose dorm is near the dining hall.
Anyway, agree that if it’s bad, the colleges will keep you indoors as much as they can. And they do run the heat. All that layering and you’ll probably be too warm, at points. Unless you arrive in a blizzard, walks will be shoveled, etc. What you miss is kids lounging on the lawn (I did have college friends who played outdoor frisbee in winter.)
My kids were also way up North and never complained about the weather, while they were there. Obviously, we visited in winter.
Think Uggs. You can get them waterproofed, if needed. I swear by mine.
It’s been around 40 here, which means no coat, it just gets thrown in the back seat of the car.
ReadytoRoll how new are you to the Northeast? Your q still sounds like a Californian question!
I would so rather tour in temps in the teens than temps in the 90s or above, personally.
Me, too. All those other hardy folks who think the heat is super and want to be out in the sun as many minutes as possible. And while all buildings have heat, not all have a/c. It’s often humid heat in the NE.
Driving and even walking can be tricky.
Good soles, no slick leather.
But really, unless you are sitting outside watching a football game, temps of 20f, even walking from building to building, won’t be a big deal as long as you have a hat, gloves and a scarf.
Don’t be shocked if you see students in shorts/flip flops.