On Aug. 21, millions of Americans will see something incredible. Will you be one of them?

A total solar eclipse will sweep across America on Aug. 21.

Millions of Americans plan to view the August 21, total solar eclipse which will sweep across the nation from Oregon to South Carolina. But there is one thing that could interfere, clouds. How likely is your view to be obstructed by clouds?

LOS ANGELES, CA (California Network) - On August 21, Americans, in particular, will enjoy a total solar eclipse that will sweep across the nation from Oregon to South Carolina. Along the path of totality, hotels are booked out, flights and train tickets are snapped up, and the roads will be congested. Tens of millions of people will attempt to crowd into a narrow band spanning the country, just 70 miles wide, to see the sun blacked out for about two minutes.

What is causing all the interest is the rarity of the event. Total solar eclipses usually happen about once every 18 months, but are visible from different places, across a narrow band. According to the statistics, a total solar eclipse is visible at a given spot on the Earth only once every 360 years, on average.

Your odds of seeing any Eclipse, even a partial solar eclipse are quite good. Partial eclipses are widely visible and occur about twice per year. A partial eclipse is when any bit of the Moon passes in front the Sun, even by a fraction.

Historically, eclipses have been considered important omens, often of bad times. Eclipses were so important they were calculated and predicted, and a missed prediction could mean death for the person responsible. In 2137 B.C., a pair of Chinese astronomers lost their heads when they failed to predict an eclipse. Meanwhile, in 1919, an eclipse was used to provide the first evidence that Einstein's Theory of Relativity was correct.

Eclipses make for lifelong memories. But even the most carefully planned trip can fall prey to mother nature. Clouds are the bane of all eclipse chasers, and there is always a chance of clouds wherever a person goes.

An interactive map, which you can view here, reveals the odds you will have to fight clouds to see the sun on August 21.

In addition to finding a cloudless sky, observers are advised to use special goggles or glasses to view the sun. The filter is intended to block out the sun's rays, which can damage your eyes. Dark welding glass also works. No matter what filter is used, it is inadvisable to look at the sun for prolonged periods of time.

For those who cannot get under the path of totality, the eclipse will be live streamed from several sites. Most observers across North America will also be treated to a partial solar eclipse, so all Americans will have the chance to enjoy something, if not the full show.