Lake Constance is a windless spot, as there is rarely a breath of air in the height of summer. ;) I definitely cannot agree with the statement "in Germany it's almost always cold anyway." That may apply in northern Germany where the weather is usually lousy. If there is still wind on nice days, then it is certainly bearable even in the blazing sun. But if you are somewhere sheltered from the wind or simply there is no wind blowing, it quickly gets warm in the sun. You can also create a heat buildup through walls or tight buildings. For example, in the picture, I can see garages and a neighboring building that could block the wind. Or if the direction is right, they can even intensify a drafty funnel.