Honestly, it depends on the furniture, but most urban outdoor furniture is not insulated in the way indoor furniture is. A lot of it is designed for durability, drainage, vandal resistance, and easy maintenance, not for keeping your backside warm on a freezing January morning. So when people ask about insulation, I’d separate actual insulation from thermal comfort. Many benches have almost no insulation at all.
Material makes the biggest difference. Powder-coated steel and aluminum look smart and last well, but they conduct heat away from your body very quickly, so they feel bitterly cold. Concrete and stone are even worse in many cases: they hold the cold and feel hard and unforgiving. Wood is usually more comfortable because it conducts less heat, and high-density polyethylene or composite slats tend to feel less harsh than metal. That does not mean they are warm, exactly, but they are less of a shock when you sit down.
Cushions are where things get complicated. In cold, wet cities, fixed outdoor upholstery is often a bad idea unless it is designed very carefully. Foam can soak up water, freeze, grow mildew, and turn into a maintenance problem. Many public spaces use removable cushions instead, often with closed-cell foam and water-repellent covers, and staff take them in at night or during bad weather. When cushions are left out, they are usually quick-drying and breathable rather than thick and plush. So the insulation is practical, not luxurious.
Design details matter too. A bench with a back and arms feels warmer because it blocks wind and reduces the amount of body heat you lose. A seat in a sheltered square, against a wall, or in a patch of winter sun will feel much better than an exposed bench on a windy corner. Dark surfaces can absorb some solar heat, and raised slats or perforations help rain drain away so you are not sitting in a puddle. Rubber feet and wooden armrests are small touches, but they stop the cold from hitting your hands and legs so directly.
In the end, urban outdoor furniture in cold winters is usually minimally insulated but carefully chosen for damage control. Metal and stone feel coldest, wood and composite are more forgiving, and removable cushions offer the most comfort when a city is willing to manage them. If the goal is genuinely comfortable winter seating, the best approach is not just thicker padding. It is better materials, wind protection, sun exposure, drainage, and a realistic maintenance plan.