What causes feeling cold on a hot day ?

Not sure.: Reasons for feeling cold: hypothyroidism, anemia (esp. W low iron or vitamin b 12 deficiency), anorexia (fasting or low body weight), chronic illnesses, chronic pain, hypoglycemia, hypothermia (low body temperature), raynaud's disease, being in cold environment, cold intolerance, anxiety or panic, cardiac or nervous system diseases, some meds as well as both viral ; bacterial infections.