I recently moved to Canada, where the winters are EXTREME.... so I know what you're going through. Anyways, mountain horse boots work really well. I got a pair and I can't live without them in the winter. The only problem I ran into is that they took a while to break in, they're stiff plastic and the first month or so it wasn't all that fun to walk in them. However, after the first month or so they were wonderful! I also invested in winter-riding pants. Mine look like snow pants, except with zippers going down the whole length and sticky rubber full seat, like the breeches. I love the zippers and the pants have saved my butt in so many snowstorms. When buying winter pants get the type that have a strap for under the shoe, it'll keep your pants in place for riding. If your barn is semi-heated there are also fleece-lined riding pants. I have pull-ons and I love them too! You can wear the fleece breeches with the winter boots under the winter pants and you'll be fine up to -30 or -40 C.
For top layers go with MANY layers. Start off with something tight (like body armor), I have basic shirts from costco, works just as well. Then add some fleece layers or something. I highly suggest a fleece vest. Then you can throw on your winter coat. Always buy one that will accommodate your extra layers. I got a big winter jacket for cheap at the hardware store. Workman's winter jackets tend to hold up better and if you can find a good deal, don't cost as much. If you get one that's baggy then you can also escape some horse biting or nibbling through all those layers! If you keep the clothes tight for the inside layers and more baggy for outside your movement shouldn't be too restricted, just make sure your first layer is super comfortable and doesn't chafe!
Other than that, always remember your hat! Get a fleece-lined hat, but one WITHOUT those poof thingys on them... horses LOVE to chew and grab them, so cut them off if your hat comes with them. Don't wear scarves, horses could pull on them or they could get stuck. Make sure your fleece and outer layers go up to your chin. If it's windy, invest in a face mask or thick bandanna. If there's snow glare get some sunglasses.
The most important part is the layers. Heated barns aren't always the very best because you always have to put on or take off layers. Most barns here keep it to around 0*c of they can afford it, but NEVER higher. If the building is insulated it will be about 5-10 degrees warmer than outside, if not insulated it could be the same as outdoors or colder. I wish you the best of luck, and hopefully this helps =)
Last edited by Indigosblue; 07-06-2011 at 08:05 PM.