The average daily temperature will be in the high 50s, low 60s. In the morning, the temperature will be in the high 30s low 40s until about 9am, when it will start to warm up.
It could be windy and very cold on the higher mountain passes (Colorado trail after miners Creek Road between Peaks 5 & 6 and the top of Vail Mountain). Temperatures could also be lower at night on Vail Mountain. Plan on carrying a jacket after Frisco, after Copper and for the climb to Vail Mountain after the Two Elk Trailhead and again after Minturn.
Snow could be present on the higher mountain passes. Expect possible thunderstorms in the afternoon. If it's raining in the valley, it will most likely be snowing above 11,000 feet.
Basically, the weather should be very nice and sunny for race weekend, but you could get rained on or snowed on. Plan accordingly!
Mountain weather can be very unpredictable. In the Colorado high country, hypothermia can be an issue for runners in any month of the year. Hypothermia dulls your brain and reduces your ability to make good decisions so think about hypothermia prevention before race day! Hypothermia can be avoided by:
1. Provide energy to your body to produce heat
2. Reduce heat loss with clothing
3. Stay Dry
4. Continue Moving
Providing energy to your body, whether solid food or warm drinks, will enable your body to burn calories and produce heat. Eat and drink regularly so that your body continues to produce heat to keep you warm. Next, wear proper clothing to retain heat and reduce wind exposure. In the mountain you should dress in layers because one moment it can be warm, the next cold. Wind exposure magnifies heat loss from bare skin. Carry extra clothing (see below). Avoid getting wet. This means that you should minimise sweating by dressing in layers and wearing waterproof outerwear to stay dry in wet weather. Lastly, continue moving. Movement means that your muscles are contracting and producing heat- this keeps you warm. As soon as you stop moving, your body reduces heat production and you will get cold. If you need to stop for a longer period of time at an aid station then wear extra clothing, drink warm fluids, eat warm food, and sit near a heat source.
The following are suggested clothing items for mountain running. Make a good decision on what to carry on race day. Remember, saving a few grammes by leaving an essential piece of clothing at home may cause you to DNF. Bringing that essential piece of clothing might cost a bit of energy, but that will keep you warm and propel you to a strong finish.
Short sleeve quick drying shirt
Long sleeve thermal top (heavier or lighter depending on expected weather)
Heavy insulation layer like down or fleece
Full length pant
Baseball type cap