Race-day weather is always a big question mark. If you're training for a marathon, triathlon, bike race, or century ride, it pays to practice in all kinds of weather. As important as it is to work on your technique, your speed, and your stamina for these endurance races, you've go to be prepared for the worst conditions on the big day and train in all types of weather. Train in the rain, on bright sunny days, humid days, unseasonably cold temps, windy days, and heaven forbid – hail. Since you can't predict what the weather will be like on the day of the race, you need to practice biking, running, or swimming in all types of weather, you'll feel much more equipped and comfortable with whatever weather blows your way.