Welcome to three-layer territory. For much of northern Europe, 5–10°C is simply *the weather* — most of winter, most of early spring. The band rewards a specific structure: shirt or tee, a genuine mid-layer, and an unlined or lightly lined jacket. Not one heavy coat — because the band spans a frosty-feeling 5°C morning and an almost-mild 9°C afternoon, and a single heavy layer can't flex across that.
The mid-layer does the real work. This is where a merino crew, a lambswool cardigan or a flannel overshirt earns its keep. The outer jacket — harrington, waxed cotton, chore coat, denim jacket over enough knit — is mostly a wind-stopper. A useful test: if you'd be comfortable standing still for ten minutes at the day's low, the stack is right; if only walking keeps you warm, the mid-layer is too thin.
Wind is the hidden variable. 8°C and still is pleasant; 8°C with a 30 km/h wind feels like 3°C. On blowy days, promote wind resistance over warmth: a smooth, tightly woven shell over a knit outperforms a chunkier knit alone, because the knit's open structure lets moving air strip its warmth straight out.
Feet and legs can stay simple. Jeans and chinos are comfortable through this band without thermals, and it's prime boot weather — leather boots or sturdy leather shoes with proper socks. Trainers are fine on dry days; canvas ones will make themselves felt on cold pavements by evening. Rain in this band is common and cold, so keep one properly waterproof jacket-and-footwear answer ready rather than improvising.
Accessories are optional but cheap insurance. A scarf and a cap cover the gap between a fine morning and a raw one, pack to nothing, and let you run the rest of the outfit lighter. If you carry a bag, throwing a beanie and light gloves in from November to March means the forecast can be wrong without consequence.
