As a running coach, the two instances in which I recommended adjusting your training are during snow and wind. This is especially true if you have a speed session planned. Running fast over snow and ice can be a recipe for slipping and possibly hurting yourself. I recommend either opting for the treadmill or moving your speed session to another day. While wind doesn’t carry the same danger as snow and ice, it does affect your pace. If you’re running into the wind, adjust your pace slower to account for the extra effort it takes to fight the wind.