Winter brings chilly temperatures, cozy nights - and the perfect excuse to bundle up with your significant other. But while you may be happy as a clam, your swimmers might not be as cheerful when you’re out and about. While the connection between heat and male fertility is often discussed, many are surprised to learn that cold temperatures can also impact sperm quality and overall reproductive function. Knowing how seasonal changes impact sperm health can help you understand your body better, especially if you’re trying to conceive.
What is the ideal temperature for sperm production?
The process by which sperm is produced in the body (spermatogenesis) is highly sensitive to temperature fluctuations. The ideal temperature for sperm production is 2 °C to 4 °C below the core body temperature. This is why the testes are located outside the body - the cooler environment is needed for healthy sperm production.
The effect of cold temperatures on male fertility
Extreme heat has long been linked to reduced sperm quality. But cold temperatures too can have an impact. A 2025 study focused on the effects of climate change on male fertility and discusses the consequences of cold stress. Available research shows that prolonged exposure to cold can lower testosterone levels, disrupt sperm production, and damage testicular cells. Cold stress has also been linked to increased inflammation and weakened sperm motility and structure. Studies also suggest that testosterone levels and sexual activity decline in winter, supporting these findings.
Low temperatures impact fertility both directly and indirectly. Cold months bring lifestyle changes that can impact reproductive health, and overall health:
Tighter clothes - While staying warm is important, restrictive clothing, such as tight underwear and thermal pants, can increase scrotal temperature. Higher temperatures in that area impact sperm production.
Less physical activity - Nothing discourages outdoor exercise like an icy environment. A lack of physical activity has been linked to hormonal imbalances and lower testosterone levels.
Seasonal diet changes - Cold-weather comfort foods tend to be higher in carbohydrates, fats, and sugars which may contribute to weight gain. Overweight men are 11% more likely to have a low sperm count and 39% more likely to have no sperm in their ejaculate.
Reduced sunlight exposure - Shorter days mean less sunlight, which can lead to a Vitamin D deficiency. While studies on the subject have led to varying results, there appears to be an agreement that vitamin D has a positive effect on male fertility, particularly through better sperm motility.
How to protect your fertility in colder months
Small changes can go a long way, especially if you’re trying to conceive. To protect your fertility during the colder winter months, wear breathable fabrics to prevent overheating and try to stay physically active. Maintaining a balanced diet rich in essential nutrients helps. Limit alcohol intake to avoid hormonal imbalances. And - stay warm, but avoid excessive heat exposures from saunas, hot baths, and heated car seats.
The YO Home Sperm Test kit can help you keep tabs on your sperm health as temperatures change. The test tests 5 key parameters, allows you to monitor any fluctuations, and records a video which you can share with your healthcare provider.
Key Takeaway
Cold winter months can introduce factors that impact male fertility. Both low and high temperatures are significantly associated with decreased semen quality. By reducing exposure to extreme temperatures, staying active, maintaining a balanced diet, and monitoring your sperm health, you can improve your chances of conception year-round.