As detailed in Fstoppers, Clear Dark Sky isn’t your normal forecast. It provides a 48-hour window into the future with a comprehensive breakdown not just of temperature, but of cloud cover, humidity, wind, transparency, and more. For natural light portrait photographers, being able to confirm cloud cover the day before a shoot — or even hours before — could save a lot time before actually heading out to a location. For night landscape and astrophotographers, looking at humidity, transparency, and darkness will let you know the best times and locations for getting the clearest views of the night sky. (Another measurement, called “seeing,” takes into account the stillness of the air, and indicates when fine details in planets will be visible through a telescope.)
The data is gathered from specific observing sites, with locations in Canada, the United States, Mexico, and the Bahamas. This means you can’t simply plug in your own location, but there is likely a site near you. In the state of Oregon, for example, 98 different sites are listed, while California has a whopping 444.
Clear Dark Sky may not initially look like the easiest forecast to read, but its color-coded graph is actually pretty simple once you get the hang of it. If you’re going for the clearest skies, just search out a block of dark blue. If you’d prefer some cloud cover, then look for white. More details on how to read the chart can be found here.