The menstrual cycle and body temperature regulation
Heatwaves are becoming increasingly frequent and intense, raising questions about their potential effects on menstrual health. One of the most common concerns is whether high temperatures can affect the length of a menstrual period or alter the menstrual cycle.
Before considering the effects of environmental heat, it is important to remember that the menstrual cycle itself influences body temperature.
Following ovulation, during the luteal phase, progesterone raises basal body temperature by around 0.3-0.7 °C compared with the first half of the cycle. In addition, the temperature threshold at which the body activates mechanisms to dissipate heat also changes.
The luteal phase and heat tolerance
Research into thermal physiology suggests that the body may begin sweating at around 37.3°C during the follicular phase, compared with approximately 38.0°C during the luteal phase. In other words, during the second phase of the menstrual cycle, sweating and cutaneous vasodilation may begin slightly later. This can moderately reduce the body’s ability to cope with intense heat.
Several studies have found that, when exposed to high environmental temperatures, some women may reach exhaustion sooner during the luteal phase. However, the findings are not consistent, and other studies have found no significant differences in physical performance.
These physiological differences may help explain why everyday activities, such as walking, working outdoors or exercising, can feel more demanding at certain points in the menstrual cycle.
Can heatwaves affect the length of your period?
Current research does not provide clear evidence of a link between high temperatures and significant changes in the length of the menstrual cycle.
The largest study carried out to date analysed nearly six million menstrual cycles recorded by more than 310,000 users of a menstrual-tracking app in Japan. The study found an association between environmental temperature and basal body temperature, but no significant association between outdoor temperature and menstrual cycle length.
It’s also important to consider that summer also tends to bring changes in several other factors that can affect menstrual regularity, including:
- Sleep disturbances.
- Travel and changes in time zones.
- Changes in diet.
- Changes in the intensity or frequency of physical activity.
- Increased alcohol consumption.
- Changes in body weight.
For this reason, attributing changes in the menstrual cycle solely to environmental temperature may be an oversimplification.
The impact of inequalities and the effects of the heat
A 2025 review published in Frontiers in Global Women's Health identifies menstrual health as one of the challenges associated with climate change. According to the authors, extreme heat and drought can make it more difficult to access water, adequate sanitation and menstrual products. These conditions may also increase the risk of urogenital discomfort and infections.
However, these effects do not affect everyone in the same way. Working conditions, housing circumstances and the financial resources available to access menstrual products can all have a significant impact on how women experience menstruation during periods of extreme heat.
From this perspective, the relationship between heat and menstruation is therefore influenced not only by biological factors, but also by the social and environmental determinants of health.
In addition, the fact that the luteal phase may be associated with a slightly lower heat tolerance highlights the importance of taking preventive measures. These include staying well hydrated, taking regular breaks, having access to shaded areas, ensuring good ventilation in workplaces and wearing breathable clothing. These measures can benefit everyone, but are particularly important for people who are more vulnerable to heat.
Warning signs related to menstruation
You should speak to a healthcare professional if you experience any of the following:
- Very heavy menstrual bleeding, requiring you to change a pad or high-absorbency tampon every hour for several hours in a row.
- Severe pain that does not improve with your usual medication or that limits your everyday activities.
- No periods for three consecutive cycles or more, once pregnancy has been ruled out.
- Persistent itching, stinging, unpleasant odour or changes in vaginal discharge.
Symptoms requiring urgent medical attention
Seek urgent medical attention or contact the emergency services if you experience any of the following:
- High temperature.
- Vomiting.
- Skin rash.
- Feeling faint or confused.
- Severe headache.
- Very hot skin.
- Loss of consciousness.
Beyond the myths
Although high temperatures do not appear to significantly affect the length of the menstrual cycle, they can influence aspects of everyday life that may have an impact on wellbeing and health. Fatigue, sleep disturbances, increased discomfort during menstruation or difficulties in storing certain medicines are some of the factors that can be affected by extreme heat.
Understanding which effects are supported by scientific evidence can help us focus on the actual risks, take appropriate protective measures and avoid oversimplified beliefs about the link between heat and menstrual health.
Information documented by:
Dr. Mª Àngels Martínez, Department of Gynecology, Hospital Clínic Barcelona.
