Reading the Chart
Clouds: the darker the blue, the clearer the sky. Low clouds block everything; thin high clouds mostly dim faint objects. Seeing is how steady the air is: good seeing keeps planets and double stars sharp; strong jet-stream winds overhead make them shimmer. Transparency is how clean the air is (humidity, haze, smoke, dust), which matters most for faint galaxies and nebulae and for the Milky Way. Darkness counts twilight and moonlight. Dew is the risk of moisture forming on lenses and mirrors.
Aurora chances come from NOAA’s Kp forecast and your distance from the magnetic pole, plus clouds and darkness. “Camera only” means a phone or camera on a long exposure may pick up a glow the eye can’t see. Look north, away from city lights.
Ratings are Doppler’s Outlook’s own estimates from forecast model data. They work best as a guide to which nights and hours to plan around.