A post by a science organization about babies being popularly conceived during the northeast monsoon, or “amihan” season, in the Philippines has caught the attention of Filipinos.
ScienceKonek, a youth-oriented science group, shared on Sunday, January 25, a possible explanation for why many birthdays occur between September and November.
“If you trace the timeline back nine months, you land right in the heart of the December-to-February holiday season,” the page wrote in a Facebook post.
Nine months is the average period for a baby to reach full term in the womb.
“In the Philippines, the cool weather brought by the northeast monsoon (amihan) typically peaks between December and February. This period perfectly coincides with a marathon of festivities: Christmas, New Year’s, and Valentine’s Day,” the organization said.
“Research also suggests that human reproduction is deeply seasonal. Cooler temperatures and shorter days can actually boost fertility and intimate activity,” it added.
The organization cited a 2018 article from The Conversation, which notes that the “seasonality of births correlates with changes in local temperature and day length.”
“Rural populations tend to have a more dramatic seasonal birth pulse than urban populations, probably because country dwellers may be more subject to environmental conditions, including changes in temperature and day length. Environmental factors like these could influence human sexual behavior,” the article read.
A women’s health medical group also suggested that December with its “extra time off, less stress, more parties, and quality time with partners,” may lead to increased intimate behaviors.
“Cuddle weather is not just a social construct, it’s in our biology!” ScienceKonek said in its post.
“Kaya madaming September, October and November babies,” a Facebook user wrote, referring to people celebrating their birthdays during those months.
“Madami talaga ang September at October babies niyan,” another agreed.
“Kasalanan pa tuloy ng amihan na lolobo ulit populasyon HAHAHAHAHA,” another Pinoy quipped.
“Totoo ‘to! Kung nagpaplano mag-baby, sulitin ang malamig na panahon,” a different Facebook user commented.
The country is currently experiencing the “amihan” season, characterized by cold, dry air and surges of low temperatures brought by northeasterly winds.
The season began in October 2025 and typically lasts until early March. “Amihan” is now at its peak and is expected to continue through mid-February.
