Stratus clouds are low, gray clouds that spread across the sky like a blanket, often covering it completely. The word comes from Latin and means “layer” or “spread out,” which perfectly describes how these clouds look: flat, smooth, and stretched across the horizon rather than puffed up or towering.

When you wake up to an overcast, dreary day with no blue sky visible, you're probably looking at stratus clouds. They typically form less than 6,500 feet above the ground, which is relatively close to Earth compared to other cloud types. Stratus clouds often bring drizzle or light mist rather than heavy rain, and they can make the whole day feel dim and gray.

Pilots pay attention to stratus clouds because low-hanging ones can reduce visibility. Meteorologists classify clouds partly by their altitude and shape, and stratus is the term for any low, layered cloud. You might also hear about stratocumulus (stratus clouds with some puffiness) or altostratus (similar layered clouds at a medium altitude).

When you understand cloud names, you can actually predict weather by looking up. Those flat gray layers mean different conditions than the towering white cumulus clouds you see on sunny summer days.