Layers are key. Even if you start out feeling cold, mucking stalls or an active ride can increase your body temperature quickly. If you overheat and sweat, you'll be at risk for a chill later. Dress in layers that can be easily removed as necessary to stay warm without sweating. Remember, you won't be able to pull a sweatshirt over your head while wearing a helmet, so stick with tops that zip or button up in front.
Fabric matters. For your base layers, choose materials that are designed to wick moisture away from your body. This keeps your skin warm, dry and comfortable. The material as well as the weave contribute to wicking, and most activewear sold today has this capacity. For the outer layers, look for fabrics that keep you warm but "breathe" to release moisture if necessary.
Treat your feet. Wear warm but thin socks that allow enough "wiggle room" for normal circulation. Silk sock liners worn under regular socks can add warmth without bulk. Waterproof or water-resistant boots are important. Remember that it's hard to keep your feet warm when they're settled in stirrups for long periods of time, so consider splurging on a set of cold-weather riding boots if you'll be riding in freezing conditions.
This article first appeared in EQUUS issue #424.