Thousands of women have taken to social media saying their menstrual cycles seemed unusually disrupted throughout June, with many claiming they either missed their period altogether or experienced two periods within the same month.

Posts flooded platforms including TikTok, X, Instagram and Reddit, with women floating hypotheses and searching for reasons for the anomaly.

One woman wrote: “I thought it was just me.”

Another replied: “Yes! Mine came twice, both full on.”

Others described late periods, unusually early periods, heavier bleeding than normal and more painful symptoms, prompting many to wonder whether the extreme weather could have played a role.

While there is currently no evidence that the recent heatwaves, which have come more regularly than some periods over the last two months, or climbing global temperatures directly caused changes to the menstrual cycle, experts do say several factors linked to extreme heat can affect the hormones that regulate menstruation.

Nonetheless, the heatwave may have created the “perfect storm”. This year’s record breaking heatwave saw the UK record its hottest June day on record, reaching 36.7°C in Somerset, while the latest July heatwave has already pushed temperatures above 35°C in parts of southern England. According to the Met Office, Britain has now experienced three major heatwaves within just a few weeks.

Although high temperatures themselves are not proven to alter menstrual cycles, they can increase physical stress on the body, raise cortisol, the stress hormone, cause dehydration and reduce sleep quality, all of which can interfere with the delicate hormonal signals between the brain and ovaries that regulate ovulation and periods.

As we previously reported, the heatwave has also triggered what researchers have described as widespread sleep disruption across Britain.

A recent YouGov poll commissioned by Greenpeace found almost two thirds of people struggled to sleep during the late June heatwave, while nearly half reported losing at least three hours of sleep per night because of the hot conditions.

A heavily discussed theory was the Strawberry Moon theory. Many users linked the timing to June’s full Strawberry Moon, claiming full moons can trigger or synchronise menstruation. Another theory, added into the conversation by one social media user, was the Summer Solstice theory, which suggests that longer daylight hours can also alter hormones affecting the menstrual cycle.

Experts say common causes of temporary menstrual changes include, but are not limited to:

• Extreme stress, whether physical or emotional
• Poor sleep
• Significant changes in body temperature
• Illness or infection
• Rapid weight loss or gain
• Excessive exercise
• Hormonal conditions such as PCOS or thyroid disorders
• Certain medications or contraception
• Pregnancy or perimenopause

Whilst theories about the cause have ranged from the effects of the heatwave and raised stress levels to moon synergy, no unequivocal reason has been confirmed for what appears to be a very strange global phenomenon.

Anyone who experiences persistent missed periods, unusually heavy bleeding, severe pain or other concerning symptoms should seek advice from their GP, as menstrual changes can have many different underlying causes.

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