Classification of exterior shoots by light conditions — Weather I (sunny, hard), II (cloudy, soft), III (overcast, rainy). Determines filter setup and lighting approach.
On set, we divide the natural light situation into three weather categories — not because we want to be meteorologically precise, but because each constellation has completely different consequences for filtering, lighting, and color temperature. This classification determines your entire filter plan and whether you need additional lamps or not.
Weather I is harsh sun — little to no cloud cover, sharp shadows, high contrast between illuminated and shaded areas. The sky appears dark blue, the color temperature is typically between 5500K and 6000K. You need aggressive ND filters here to keep the aperture open, and a polarizing element helps against reflections. For faces, you often need fill light or reflective surfaces to break up the shadows under the eyes. The classic problem: the sun comes from diagonally above, casting black holes under the eyelids. A freshly stretched Grifflon or a silver bounce board will be your best friend here.
Weather II is thin cloud cover — diffused light, but still with a definable direction, the sky is grayish-pale with the sun disc visible. This is actually the ideal condition: you have natural fill components, the contrast is controllable, and the color temperature is around 6500K. You need less or no additional lighting. The filter plan is moderate — often an ND 0.6 or 0.9 is sufficient. The shadows still have detail but don't appear brutal. Many DoPs wish for Weather II permanently.
Weather III is overcast gray sky — no discernible sun, flat, diffused all-over light, practically no shadows. The light comes from all directions simultaneously, the color temperature gets colder (6800K to 7200K, often with a blue component). For color-warm scenes, you'll need CTB filters or you'll adjust in post-production. The advantage: no need to track the sun, consistent illumination for hours. The disadvantage: the image appears flat without artificial key light. You will almost always use a softbox or a spotlight here to bring modeling back to the face.
The weather classification is not dogma — it is a tool for quick communication with the gaffer, for planning filter sets, and for estimating the lighting budget. On a day with changing conditions, your setup can flip three times in four hours. The scouting visit is therefore not optional: you need to know the shadow direction, how long the sun really shines, and whether the wind is shaking trees that turn your Weather II into III.