For those who wonder -3°C is about 26°F.
Freezing, quite cold but nothing too serious.
Now depends what you intend to do;
* Are you sleeping outside, in tents, or hotels?
* Would you hike for one day, overnight, a few days?
* Do you plan outdoor walking or is it "ordinary" tourism (sleeping in hotels, visiting monuments...)?
* Do you need a somewhat formal clothing? Casual? Is mountain/sport clothing Ok?
We had recently temperature like -10°C during night, -7°C during day. One or two wool (at least half percentage) pull overs, a casual winter jacket, jeans pants and cotton socks were ok for city tourism/casual walk, but I support cold weather pretty well.
Improvements would be:
* first: woolen socks and woolen hat
* then more/thicker pullovers
* then some more thermal pants
What you need is:
* underwear that won't keep moisture against skin: wool or technical materials
* some insulation, preferably wool or polartech type material (breathable)
* some breathable windbreaker shell (most winter jacket outer fabric act as a good enough shell, no need for goretex)
As a rule of thumb, lower body part needs about one third of the insulation for upper body part.
You should avoid to be to get too hot in your clothing because you'll start sweating heavily which will decrease insulation effectiveness aside from other problems (discomfort, smell...). Having many thin layers is better than one thick one as you will be able to adjust your insulation to your current activity.
When active (quick walking...), remove clothes (activity will keep you warm anyway), when stopping, put more clothing on. Repeat as often as necessary.
The most performant system is down jacket (or synthetic filled equivalents) that gives the best weight/insulation ratio (they are very compressible too, particularly down), but they are expensive and quite fragile.
PS:
as for brands, my personnal choice is Ullfrotté/Woolpower, more on the thermal side of spectrum/stationary activity, for more active occupations, I'd probably go for Odlo.