Thousands of UK women have taken to social media to report having two periods in June or missing one entirely, sparking widespread speculation. TikTok videos from users like Oz and @thrivingwithhannah describe late periods or double cycles. Oz shared her period was 13 days late 'and counting,' while @thrivingwithhannah noted one daughter missed her period completely and another had two.
Heatwaves and Hormones: The Science Behind the Cycle
While some joked about aliens or the moon, experts point to recent heatwaves as a likely factor. Since May, the UK has experienced three heatwaves, with June breaking temperature records at 37°C in East Anglia. Scientists estimate over 2,700 deaths in England and Wales during these periods were directly linked to heat, attributed to climate change.
Pharmacist and TV health expert Thorrun Govind explains that the menstrual cycle is sensitive to changes in the body. 'Disrupted sleep and heatwaves can impact it,' she says. Heat can cause dehydration, physical stress, and poor sleep, all of which 'may contribute to temporary changes in the menstrual cycle.' She adds that a late period is surprisingly common and not always a sign of pregnancy.
Women and Heat: A Disproportionate Impact
Heatwaves disproportionately affect women. Men sweat more, cooling down effectively, while women struggle to release heat and take longer to start sweating. Being on your period can increase body temperature by 0.3–0.7°C, compounding the effects of high outdoor temperatures. Professionals have likened heatwaves to a 'stress test' on women's cardiovascular systems.
Can a Heatwave Cause Two Periods in One Month?
Dr Babak Ashrafi, a GP at Superdrug Online Doctor, notes that the average cycle is 28 days, but a healthy cycle can range from 21 to 35 days. This makes it entirely feasible to have two periods within the same calendar month, especially if your cycle is shorter or ovulation happens earlier. Polyendocrine Metabolic Ovarian Syndrome (PMOS, formerly PCOS) and thyroid disorders can also cause irregular periods.
Dr Suzanne Wylie, GP and medical adviser for IQdoctor, says the evidence that hot weather directly influences menstrual cycles isn't concrete, but the symptoms heatwaves induce can have an impact. 'Our reproductive hormones are quite sensitive to what's happening elsewhere in the body,' she explains. 'These effects are likely to be quite modest; they won't happen to everyone, and I certainly wouldn't expect a heatwave on its own to cause widespread disruption to menstrual cycles.'
When to Seek Medical Advice
A period is considered late if it hasn't arrived seven days or more after expected. Dr Babak advises that if you've had unprotected sex and your period is late, pregnancy should be considered. Home pregnancy tests are most accurate from the first day of a missed period. If the test is negative but your period still hasn't started after a few days, repeat the test or speak to a healthcare professional. If periods remain irregular over several months, or you experience unusually heavy bleeding, severe pain, or bleeding between periods, seek medical advice.
Millions Using Wrong Painkiller for Period Cramps
Separately, a study published in PLOS Digital Health analyzing 211 million supermarket receipts between 2006 and 2015 found that millions of people overwhelmingly reach for paracetamol for period pain, but ibuprofen is actually more effective for cramps. The research was conducted by experts from the University of Bristol and the University of Nottingham.
