The best astronomy weather in the world can be seen at the La Silla Observatory in Chile.

Robert Fosbury, an astroomer based at ESO headquarters in
Germany wrote about solargraphy as follows:  

"Solargraphy, the art of using a single long-term exposure with a pinhole camera to photograph the movement of the Sun over the course of many weeks, helps show just why the La Silla Observatory is one of the best in the world. The white streaks across the top of the image are the Sun’s progress across the sky over the whole period. When clouds come between the Sun and the camera, breaks in the streak form but, as can be seen here, almost no clouds obscured the sky during the entire exposure. Perfect astronomy weather in other words!"