Why do we feel hot even when temperature is below our body temperature

Some of you must have noticed that we start feeling heat even when temperature is much below our body temperature. Scientifically thinking, we should not feel hot till the temperature does not go above 38 degree Celsius. But in reality we start feeling hot as the temperature rises above 30. Is there something wrong with our senses or our normal body temperature is quiet low than what we were told. Truth is somewhat different as our senses are correct and normal body temperature is also around 37 degrees.

Why do we feel hot even when temperature is below our body temperature ?
To understand that why we feel hot even when temperature is several degrees below body temperature, we need to know more about our body's functioning. Our body is a continuously working machine, and like every machine it radiates some heat. Our internal functions like pumping by heart, muscle movement, digestion of food and several other metabolic functions creates heat as a byproduct. Our body expels heat through skin. It radiates heat easily if the temperature of atmosphere is several degrees below body temperature. If the atmospheric temperature rises then it become harder for our skin to expel heat.
We the humans are only animals that wear clothes which makes our skin struggle more to expel heat. This is another major reason that we feel hot even before atmospheric temperature reaches our body temperature. During winters the same clothes help us in maintaining body temperature and save us from chill outside.

Humans are warm blooded animals and our body is designed to expel heat through various mechanisms. Some of them are discussed here.
Through Blood Circulation: Arteries and Veins are basic part of our blood circulation. Major arteries are normally much below the skin and deliver the oxygenated blood to all organs. Deoxygenated blood is then carried by our veins, which are normally superficial and appear blue at several parts of body. Here blood also carries the heat from internal organs to the superficial skin, which is the main heat radiator of our body. The purpose of veins being near the external skin is also explained by this fact.
Sweat Glands: Sweat glands present in our skin solve two purposes. They excrete some toxins through sweat and help is cooling down the body. As the external temperature rises above 30 degrees, we start producing sweat and utilizes our body heat to evaporate it, which cools the body down. If the humidity level is low in air, then this mechanism works perfectly.
Body Hair: Body hair play an important role in trapping and expelling body heat. When the lie flat on the body surface they expel heal, and trap it when the stand straight with the help of tiny muscles in the skin. These muscles are involuntary and function automatically when our body need it. You must have noticed their function, while changing clothes during winters, as we get goosebumps to save the body heat.

If the humidity level is high and the temperature is also high then it makes us sweat more as it does not evaporate due to humidity in air. It disturbs the purpose of sweating and we feel even more hot.

Reference:
https://www.scientificamerican.com/article/why-people-feel-hot/