How is the sultry weather without the sun formed?

If it's windy in summer, it won't feel hot. Generally, it will feel very hot before it rains heavily. This is because before the rain, although the cumulonimbus clouds blocked the sunlight, the air was very humid. Our bodies dissipate heat through sweat, which takes away heat when it evaporates. However, when the air is humid, sweat is difficult to evaporate, causing sultry heat.