Man blows up water balloon

You Aren’t Imagining Things—Summer Penis is 100% Real

A urologist breaks down the phallic phenomenon.


verything seems bigger and better in the summer. The days are longer. The grass gets taller. The temperature is higher. Even your junk might be bigger. MEL Magazine coined the term “summer penis” in a mini 2018 investigation on men who claim their flaccid penis gets bigger in warmer months. 

But is summer penis a real phenomenon or just in men’s minds? We asked a doctor. 

What is Summer Penis?

Men have been sharing anecdotal accounts of larger, summer packages on Reddit as early as 2013. 

“It’s definitely real. More noticeable from my balls hanging more but soft size is a little bigger too,” a member of the r/bigdickproblems subreddit wrote. 

“As a grower—I cannot wait till summer. Summer penis is 1000% a thing,” another reported.

It seems like the well-endowed guys of Reddit have come to a consensus that summer penis is real, but what about docs?

“I have had patients tell me that the temperature of the room or cold temperatures outside impact their genital size and retraction,” says Amy Pearlman, M.D., a board-certified urologist. 

What Causes Summer Penis?

Your testicles are surrounded by several layers of tissue, including the dartos muscle, Pearlman explains. That muscle contracts, causing wrinkles, or relaxes the skin on the scrotum in response to temperature changes. The dartos muscle promotes spermatogenesis (the creation of new sperm cells), which can only occur under specific internal temperatures. 

This contraction or expansion of this muscle may also impact how long your flaccid penis looks as the skin tightens or loosens around your scrotum. 

Think about it like this: When it’s cold outside, you’ll cross your arms and shrink yourself to preserve your body heat. “When the dartos muscle contracts, the penis retracts inward, shortening its length,” Pearlman says. “Cold temperature and stress may both lead to contraction of this muscle with subsequent penile retraction.”

When it’s hot out, you might relax and spread your arms out to try to cool down. “In warmer temperatures, the dartos muscle may relax, which can result in a larger [looking] penis,” Pearlman explains. 

High temperature and humidity can also boost blood flow to your skin, which may make you appear girthier when flaccid.

Warm weather and sex drive

The motion in the ocean, not just the size of the waves (if you get my drift), may also get a boost in the summer. Research shows that warmer weather may increase your sex drive.

In the summer, melatonin levels (the hormone your brain produces in response to darkness) decrease. Melatonin may block sex hormones like testosterone, which means that getting a little less might spike your libido (1). 

Cold outside but want a bigger penis?

Want to reap the effects of summer penis year round? 

Pearlman suggests “applying a warm towel to the penis or hopping in a hot shower to help improve blood flow to the tissue and help the dartos muscle relax.”