The penis is highly sensitive and contains over 4,000 nerve endings in the glans alone. However, for many reasons, a man's sensitivity can drop to where the penis feels cold and tingling, like he's not quite as erection-ready as he used to be. It can be a sign of low testosterone (low T), some medications, certain health conditions and even habits and activities like smoking, sedentary lifestyles, tight or uncomfortable underwear or long cycling rides.
Changing positions, getting up, and switching to a looser or more comfortable pair of underwear can often restore sensations to the tip of the penis and the area between the glans and the anus (known as the perineum). In some cases, this feeling can be caused by sitting for prolonged periods of time, wearing tight clothing, or friction from sex toys and cock rings that can rub against the skin of the penis or perineum.
Underlying health conditions such as Raynaud's disease, hypothyroidism, and peripheral artery disease can affect blood flow to the penis and other body parts and may lead to feelings of coldness in the area. In addition, stress and anxiety can cause the body's "fight or flight" response to constrict blood vessels and reduce the amount of blood flow to different areas including the genital region.
Infections of the urethra, such as urethritis and urinary tract infections (UTIs) can also cause a cold sensation in the tip of the penis. If a person's penis feels cold, is painful, or has a discharge from the urethra it could be a symptom of a serious condition called Meatal Stenosis, which is the narrowing of the urethral opening in the tip of the penis.