Well, it regularly gets colder than that in the winter where I live so here is some advice from a Canadian...

Wear layers.

Put on a light shirt as your under layer. Something that is polyester/lycra is good because it will wick moisture away from your body (you still sweat even when you are cold). Then you will want a normal sweat shirt, just about any kind is good provided it is breathable. Wool is great for a second layer.

For jackets, nothing beats down jackets... they will be very puffy but very warm. A nice plus is if you get one with a down hood you don't need to carry around a hat (or toque, in Canada) with you. If it doesn't have a hood, look for a wool hat (Toque, eh) and make sure to get one that goes all the way down over your ears so you don't get frostbite.

For gloves I would recommend two pairs... a big thick pair to wear most of the time, and a small thin pair to wear when it gets warmer (or if you are exerting yourself and getting warm). Don't layer them though - switch between them.

For socks, I would highly recommend wool socks, because they are very warm and will stay warm even if they get wet (again the sweat thing). Don't layer socks because that will cut off blood flow to your feet, putting you at risk for frostbite.
For boots... go to a hiking store and get a good pair of hiking boots, possibly with reinforced (but not necessarily steel) toes. A good sturdy pair of hiking boots will keep your feet warm, and dry (by keeping the snow out). As well if you are walking through rock and ice you will have a good grip and won't be worried about smashing your toes.

Pants are a tough one... don't wear jeans because they really don't keep you warm. First I would get long johns (long underwear) that are like your first layer shirt - polyester/lycra so they wick the moisture away. Then probably a pair of sweat pants, or at some outdoors stores you can get fleece lined track pants - those are great. If it's going to be really cold and windy, you might consider an outer shell that acts as a windbreaker.

The reason layers are important... 3 layers traps more air than one bulky layer and keeps you warm. Also if you start to warm up, take off a layer, don't totally strip down. If you strip down to your last layer when you are warm, your sweat will cool off too quickly and you might get hypothermia. This is why the two gloves too...

Take care to keep your clothes dry, and don't wear them if they are even a bit damp. Damp clothes will suck the heat out of your body very quickly.

Last but not least drink lots of water, it is easy to get dehydrated in the winter, especially if you are exerting yourself.
Seeing that the altitude there is about 500 feet, you really don't have to worry about altitude sickness, so that's a bonus. Just keep in mind that if you can't stop shivering, that is hypothermia and you have to get somewhere warm ASAP.

Good luck and have fun!