Why Hot Weather Makes Testicles Hang Lower: A Medical Perspective

As temperatures rise during summer, many men notice that their testicles seem to hang lower or appear looser, leading to the popular phrase "summer long balls." This phenomenon, while often joked about, is grounded in human physiology and is an elegant example of the body's natural temperature regulation system for reproductive health. In hot weather, the scrotum and surrounding tissues adapt by loosening, allowing the testicles to hang lower and more exposed to cooler air, which helps keep sperm production and hormone regulation optimal.

The journey of the testes begins in the abdomen during fetal development. They then descend through layers of the abdominal wall into the scrotum—a crucial move for maintaining the ideal temperature for sperm creation. The descent is a complex process and sometimes can go incomplete, resulting in an undescended testicle, which may require surgical correction.

Once in the scrotum, the testes are constantly adjusting their position. The cremasteric muscle can contract to pull the testes closer to the body for warmth or relax to allow them to hang lower when it's hot. This reflex can be tested by stroking the inner thigh, which may cause the testicle on that side to rise temporarily. The dartos muscle also contracts or relaxes to modulate the position of the testes according to external temperatures.

This dynamic regulation is vital for fertility. Sustained heat exposure can impair sperm development, which is why men trying to conceive are advised to wear looser underwear and limit activities like cycling that increase groin heat. The pampiniform plexus, a network of veins around the testicular artery, acts like a radiator. It cools arterial blood before it reaches the testes, and conditions like varicocele—swelling of these veins—can impair this cooling process, potentially leading to fertility issues.

Overall, the changes in testicular position during hot weather are a normal, healthy response. They indicate that the body is effectively managing testicular temperature to support reproductive functions. If your testicles appear to hang lower or feel looser in summer, it’s a natural adjustment, reflecting your reproductive system working as intended.