Idaho A sure way to ruin a vacation is to encounter weather that's not expected. Since it can't be forecast more than a week or so in advance, weather averages serve as much better indicators of what to expect any month. 5,980 feet Like other parts of the West far from the Pacific Ocean, Sun Valley is dry, with only a little over 17 inches of precipitation a year. Most of that falls as dry, powdery snow from November through March. As in other dry areas, the sky in this region of south-central Idaho is clear much more than it's cloudy.
Clear skies allow the sun to warm the ground and the air near it during the day.
But clear skies also allow the ground's heat to radiate away at night. This is why the average range between high and low temperatures is more than 30 degrees. The latitude and longitude above can be used on a U.S. Naval Observatory Web site to find the time of twilight, sunrise, sunset and moon rise and moon set for any location on Earth. Click here for a link to this site. Precipitation, which includes rain and melted snow or sleet, and snowfall are in inches.