Rittou and 639Hz | The Day Winter Is Named — Japan’s Solar Term of Fire and Gathering

There is a morning when you open the window and the quality of the air has changed. Not cold, exactly. Dry. The wind that felt faintly damp yesterday goes straight past your cheek today. From that morning on, the stars begin to look suddenly close. And people, for no reason they can name, feel like reaching out to someone.

The name given to that doorway is Rittou — literally, “winter stands.” The beginning of winter, on the calendar. What follows is the story of the solar term Rittou. And its slow resonance with 639Hz — the Solfeggio tone traditionally said to stand for connection.

The answer, in three lines Rittou is the nineteenth of the 24 solar terms, the day the sun reaches 225° of celestial longitude (around November 7 in 2026). On the calendar, winter begins here: sasanqua camellias bloom, and the ground starts to freeze. Solfeggio 639Hz is traditionally associated with relationship, connection and harmony — which sits poetically alongside Rittou’s rites of fire and gathering (Robiraki and Inoko). There is no historical link between the two, and nothing here claims an effect.

💎 The one line of this article What Rittou teaches is that the coldest night is the night you are most directly connected to the sky. Which is why people gather around a fire.

The 30-Second Summary

• Rittou is the nineteenth of the 24 solar terms — the day the sun reaches 225° of celestial longitude, around November 7 in 2026 (dates shift by a day depending on the year, so an annual almanac is the reliable source)
• It is one of the four “standing” terms (Risshun, Rikka, Risshuu, Rittou) — the doorway into a season rather than its middle
• Its three micro-seasons are “camellias begin to bloom” → “the earth begins to freeze” → “the golden cup blooms”
• That “golden cup” is not the marigold it sounds like — it is said to describe the narcissus, whose small yellow corona was likened to a cup of gold
• Japan’s meteorological agency announces the season’s first winter wind (“kogarashi No. 1”) for only two regions — Tokyo and Kinki. It is not a nationwide term
• Clear, still nights are the coldest ones. With no clouds to reflect it back, the ground’s heat escapes straight into space — radiative cooling
• 639Hz is traditionally described as the tone of relationship, connection and harmony
• In equal temperament at A=440Hz, it falls almost exactly between E♭5 (about 622.25Hz) and E5 (about 659.26Hz) — a tone belonging to neither key
• All of this is symbolic language, not a claim of scientific effect

1. What Rittou Is — The Day Winter Is Named

Rittou is the nineteenth of the 24 solar terms, the traditional East Asian division of the year into 24 parts based on the position of the sun. It marks the day the sun passes 225° of celestial longitude. In 2026, Rittou falls around November 7. (Because these dates depend on solar position, they can shift by a day from year to year. The annual almanac published by a national observatory is the dependable reference.)

Rittou is one of the four “standing” terms — Risshun, Rikka, Risshuu, Rittou — the four doorways of the year. What is striking is that Rittou is not “the day it got cold.” It is the day it will get cold. In early November, many years are still mild at midday. And yet the calendar declares winter ahead of the body.

Why? Because the solar terms are measured by the height of the sun, not by temperature. Heat lags behind light. The ground and the sea hold what they absorbed, then release it slowly — and that delay is the gap between the almanac and the skin. Rittou, then, is the day the light becomes winter, before the air does.

For the term just before this one, see

Soukou and 417Hz — When Dew Becomes Frost

2. The 72 Micro-Seasons of Rittou — Camellia, Frozen Ground, and a Cup of Gold

Each solar term divides again into three micro-seasons. For Rittou, they run:

• Tsubaki hajimete hiraku — camellias begin to bloom
• Chi hajimete kōru — the earth begins to freeze
• Kinsenka saku — the golden cup blooms

Two of these three are easy to misread. The first: the characters read literally as “mountain tea,” a Chinese term for the camellia family. But the flower that actually opens in Japan at this hour of the year is usually the sasanqua (Camellia sasanqua) — and the old name has been carried over to the flower at hand.

The third: “golden cup” is not the marigold whose Japanese name sounds identical. Look into a narcissus and you find, at the center of the white petals, a small yellow cup. That corona was likened to a cup of gold, and the micro-season took its name. So the sequence reads: bloom (camellia), freeze (earth), bloom (narcissus).

Flowering appears twice inside a season that is hardening. Winter is not the season when things stop. It is the season when what blooms changes.

3. The First Winter Wind — And Why Only Two Regions Announce It

Around Rittou, the Japanese news begins to mention “kogarashi No. 1” — the season’s first withering wind. What surprises many people is that this announcement is made for only two regions: Tokyo and Kinki. There is no “first winter wind” for Hokkaido or for Kyushu. The reason usually given is that kogarashi was never a nationwide technical term — it was a local word, grown from how a particular place experiences its own weather.

Conditions vary by region, but broadly the wind must arrive

• within a defined window
  from mid-autumn into early winter
• under a winter pressure pattern
  (high to the west, low to the east)
• from a direction between
  west-northwest and north
• at a maximum speed of
  roughly 8 meters per second or more

Some years, no wind qualifies — and the season passes with no No. 1 at all. What is worth pausing on is the impulse itself: someone decided to number the wind. Wind cannot be seen. It leaves no shape. And still, people wanted to count the first breath of the year. To count something is to enter a kind of relationship with it.

You give it a name, assign it a number, and quietly assume you will meet again next year.

4. Why the Winter Sky Turns Clear — And Why the Stars Will Not Hold Still

After Rittou, the night sky changes. Not because there are more stars. Because the air has changed. Under a winter pressure pattern, dry continental air flows in. Cold air can hold far less water vapor, and less vapor means less to scatter and blur the light. Colder ground also weakens the vertical mixing of air, so dust and smoke are stirred up less.

The result is a sky of high transparency. And yet — here is the contradiction — winter stars twinkle more, not less. Clear, but restless. The usual explanation is the jet stream, which sits strongly overhead in this season. When fast, turbulent air moves high above you, starlight passing through it shimmers.

So the winter sky is easy to see through, and never still. Transparency and calm turn out to be two different things. Which is not so far from what happens between people. The better you come to see someone, the more of their unsteadiness you can see too. Clarity does not promise quiet.

5. Radiative Cooling — The Coldest Night Is the Connected One

From Rittou onward, the morning chill becomes unmistakable. And strangely, the morning after a clear day is the coldest. The mechanism is radiative cooling. By day, the ground absorbs heat from the sun. By night, it releases that heat as infrared radiation. When clouds are present, part of that outgoing heat is reflected back down.

A cloud layer works like a blanket over the ground. On a clear night, there is no blanket. The ground’s heat travels straight out into space, with nothing in the way. So it cools. And if the wind is weak, the chilled air is never stirred, it pools at ground level, and the cold deepens further.

Here is the heart of this article. The coldest night is the night the ground and the cosmos are directly connected. That the clearest, most star-filled nights are the cold ones is not a coincidence. Seeing well and losing heat are two faces of a single fact: that nothing stands between.

That the distance has closed.— And on exactly those nights, human beings gather around fire. They grew cold, so they moved closer. That the rites of Rittou cluster around fire and company is probably no accident at all.

6. What 639Hz Is — The Tone of Relationship

639Hz is the third of the six Solfeggio tones most often listed — 396, 417, 528, 639, 741, 852. In the traditional telling, it is associated with

• relationship between people
• connection and harmony
• being understood, and speaking

In chakra systems it is often laid over the fourth chakra (Anahata, the heart). For more on this tone, see

639Hz — The Frequency of Connection and Love

and The Complete Guide to 639Hz A short note on tuning. In equal temperament with A=440Hz:

• E♭5 is about 622.25Hz
• E5 is about 659.26Hz

639Hz falls between them. Roughly 46 cents above E♭, roughly 54 cents below E. A semitone is 100 cents — so 639Hz sits almost exactly in the middle of two neighboring keys. Last month’s 417Hz was only 7 cents from A♭: almost the same note. 639Hz is the opposite case. It is as far as possible from both.

A piano cannot play it. And still, no position could suit the theme of relationship more precisely. A relationship does not live inside either person. It appears in the place that belongs to neither of them.

7. What Is Said About “639Hz Effects” — Drawing the Honest Line

Here is our honest accounting of the claims made for 639Hz. What is said (its traditional position)

• In the modern Solfeggio tradition, 639Hz is presented as a tone for repairing relationship and for speaking what is unsaid
• Placed at the heart chakra, it is described as balancing receiving and offering
• That shared musical experience — singing together, listening together — can affect feelings of social connection has some research support in choral and music-therapy literature. That finding is about shared music, not about 639Hz specifically
• A steady background tone may make a conversation feel less tense. Again, that is a general property of sound environments, not of one frequency

What cannot be said (not a scientific claim)

• There is no established scientific evidence that 639Hz repairs human relationships
• Claims that it moves another person’s feelings or attracts connection lack peer-reviewed support
• No causal link has been demonstrated between listening and improved relationships
• The Solfeggio system itself is a relatively modern reconstruction popularized in the late twentieth century — not an unbroken ancient tuning system

So 639Hz is best held not as a magic tone that changes relationships, but as a symbolic tone for quietly remembering someone. That said, the pull toward company as the cold arrives is an entirely natural feeling.

8. The Symbolic Link Between Rittou and 639Hz

To be direct: there is no historical or textual link between the solar term Rittou and Solfeggio frequencies. The 24 solar terms were systematized in ancient China. Robiraki and Inoko grew in medieval Japan and after. The modern Solfeggio system spread from the late twentieth century.

Different eras. Different cultures. But laid side by side as structures of theme, a soft resonance appears.

• Radiative cooling means nothing stands between ground and sky — connection shows up first as cold
• The cold drive people toward the fire — closeness usually begins on the side of weakness
• 639Hz falls between two keys — a relationship cannot exist in one person’s territory alone

So the suggestion is this: “Play 639Hz softly, and bring to mind one person who has drifted a little further away.” Held against Rittou’s own theme — opening the fire, inviting people in — the two can be tasted together, poetically. Not as an academic claim. As one way of reading symbol against symbol.

9. Soukou, Rittou and Shousetsu × Frequency — A Symbolic Comparison

Below is a comparison table placing Rittou between its neighbors.

※ This mapping is a poetic guideline only, not a claim that a frequency can alter a season.

10. Living with Rittou and 639Hz — Small Habits of Fire and Memory

A few concrete ways to spend this term.

• Make the first heating of the year slightly ceremonial: before you flip the switch, look around the room and take one deep breath. Robiraki was never only about swapping equipment — it was a way of telling yourself the season had turned. A few seconds is enough
• At night, play 639Hz softly and bring to mind one person who has drifted further away: you do not have to contact them. You do not need a reason to. Remembering is far enough. Neither low nor high, 639Hz sits quietly behind this kind of thinking
• On a clear night, step outside for five minutes: after Rittou the air dries and the stars come close. If you feel the cold, that cold is evidence that nothing stands between. Knowing that chill and clarity are one thing changes what the cold means

On building an evening habit around sound, see And for those who want a more careful form of “bringing someone to mind,” there is an old one: These are offered as habits of rest and reflection. They do not guarantee improvement in physical or psychological condition.

11. Safety and Cautions

A few lines worth holding at this time of year.

• Inspect heating equipment before you use it. Do not run a device that has been stored for six months for hours on end straight away. Dust burning off, unfamiliar noises, a frayed cord — stay nearby for the first thirty minutes. That the old rites tied fire-opening to fire protection reflects a real seasonal danger
• Pair heating with ventilation. Rooms with combustion heaters need regular air exchange. Playing music encourages sealed windows — let a timer double as your ventilation cue
• Do not load “I must fix this relationship” onto a tone. 639Hz is presented as the frequency of connection, but listening guarantees no change. Turned into a source of urgency, sound stops being rest
• Do not push your body through sudden cold. Moving from a warm room into a cold one puts real strain on the body. Around bathing and early-morning departures especially, shrink the temperature gap
• Do not treat low mood at the start of winter with sound alone. Shorter daylight makes mood fluctuation more likely. If low mood persists beyond two weeks, consult a professional rather than a playlist. 639Hz is not a substitute for medical care or counseling

12. Cultural Background — Robiraki, Inoko, and the Opening of the Kotatsu

The customs around Rittou cluster around one thing: fire. The first is Robiraki — “opening the hearth.” In the world of tea, the portable summer brazier is put away, and the sunken hearth cut into the tatami is opened for the cold months. At the same time comes Kuchikiri — the cutting of the seal on the jar of new tea picked in early summer and left to rest.

Because the two coincide, Robiraki has long been called “the New Year of tea people.” The year begins again, there. The second is Inoko. On the day of the boar in the tenth lunar month, at the hour of the boar, people ate inoko mochi — a custom traced back to the Chinese genchō. The boar, which bears many young, became a symbol of descendants and continuity.

And in five-phase thought, the boar belongs to the element of water. Water governs fire. So a fire lit on that day was believed to be spared from burning down the house — which is why Robiraki and opening the kotatsu came to be scheduled on the day of the boar. In parts of western Japan, children still go from house to house striking the ground with a roped stone — the inoko-tsuki.

The third is Shichi-Go-San, November 15. Once the hearth is lit and the house is warm, families go out together to mark a child’s growing up.— Set side by side, these customs share one feature. Not one of them can be done alone. Opening a fire. Handing out rice cakes. Walking a child somewhere.

The cold drove people indoors, and indoors, they drifted toward each other. The rites at the start of winter may simply be the name given to that movement: they grew cold, so they came closer.

13. The Sound Environment of Early Winter — A 5-Point Checklist

After Rittou, the air in the room and the temperature of the bed both shift to winter settings. Five points for tuning warmth and sound together.

1. Do you know what your heater sounds like? Fan noise fills a wide low band. Rather than raising the music, dropping the fan one step often makes the room quieter overall
2. Can the sound stop itself? The longer the nights, the more often you fall asleep with something playing. Decide the timer before you press play
3. Are you handling humidity before sound? Heating dries the air and irritates throat and nose. The same tone is harder on the ears in a dry room
4. Is there localized warmth for feet and back? Warming the ankles down and the back shifts comfort more than raising the whole room. A hot water bottle, a lap blanket, thick socks
5. Have you switched the bedroom over? Autumn bedding leaves you cold near dawn. See also How to Set Up Your Bedroom

None of this requires expensive equipment. Lower the fan. Warm your feet. Let it turn itself off. — Those three are enough for a Rittou evening.

About This Article (Disclaimer and Advertising Notice)

This article is informational content introducing the symbolic meanings of culture, calendar and frequency. It is not a substitute for medical care or counseling. Nothing written here about 639Hz or the 24 solar terms is intended to guarantee improvement in physical condition, symptoms or personal relationships, and individual responses vary. If low mood or ill health persists, please consult a medical professional rather than relying on sound. Readers with existing conditions or hearing concerns should consult a specialist before listening. When using heating appliances, follow the manufacturer’s instructions and safety notices.

[Advertising] This article may in future contain affiliate links (links introducing products or services). Purchases made through such links carry no additional cost to the reader.

14. For Example, Consider a Scene Like This

To make the idea concrete, let us imagine one general situation (this is a fictional, generalized example and not the true story of any specific person). Suppose there is someone you have not written back to. There was no argument. You did not stop liking them. You simply missed the moment to reply, and a whole season went by.

At times like this we usually blame ourselves. If only I were better at keeping in touch. But step outside on a Rittou night, look up at the stars in the cold air, and something becomes visible. It is cold because nothing stands in the way. With cloud, the heat comes back down. You stay warm.

But then the sky is invisible.— The feeling that someone has grown distant also means you can still see them. We do not remember the people who stopped mattering. Play 639Hz softly and bring their name to mind, just once. You do not have to write. You do not have to decide anything.

Nothing will change that night. But the sense of “they have drifted away” becomes visible as not a failure — a state with nothing in between. The important part: the sound does not rebuild the relationship for you. 639Hz is only the background against which you allow yourself to remember.

📚 Related Articles

• Traditional Tanabata and 639Hz | The Night the Stars Reunite, and the Frequency of Connection
• Soukou and 417Hz | When Dew Becomes Frost — What Japan’s Last Autumn Solar Term Really Means
• Kanro and 174Hz | When the Dew Turns Cold — What Japan’s “Cold Dew” Solar Term Really Means
• Shuubun and 528Hz | The Day Light and Dark Weigh the Same — What Japan’s Autumn Equinox Solar Term Really Means

FAQ (10 Questions)

Q1. What kind of day is Rittou?

It is the nineteenth of the 24 solar terms, the day the sun passes 225° of celestial longitude. It marks the beginning of winter on the calendar and is one of the four “standing” terms alongside Risshun, Rikka and Risshuu.

Q2. When is Rittou in 2026?

Around November 7, 2026. Because the solar terms depend on the sun’s position, dates can shift by a day, so an annual almanac is the reliable reference.

Q3. Why is it still warm at Rittou?

Because the solar terms are based on the position of the sun, not on temperature. Ground and sea release stored heat slowly, so air temperature lags behind the light. The calendar normally arrives a little ahead of the body.

Q4. What are the micro-seasons of Rittou?

“Camellias begin to bloom” → “the earth begins to freeze” → “the golden cup blooms.” Notably, flowering appears twice inside a season that is otherwise hardening.

Q5. Is “the golden cup” the marigold?

It is said not to be. “Golden cup” refers to the small yellow corona at the center of a narcissus, likened to a cup of gold. The micro-season marks the narcissus coming into bloom.

Q6. Is the “first winter wind” announced nationwide in Japan?

No. Only two regions — Tokyo and Kinki — receive an official “kogarashi No. 1” announcement. In some years no wind meets the criteria and the season ends with no No. 1 declared.

Q7. Why is the morning after a clear day so cold?

Radiative cooling. Clouds reflect escaping heat back toward the ground like a blanket; on a clear night that blanket is missing and the ground’s heat travels straight into space. Weak wind lets the chilled air pool, deepening the cold.

Q8. What is Solfeggio 639Hz?

The third of the six commonly listed tones, traditionally associated with relationship, connection and harmony. In equal temperament at A=440Hz it falls almost exactly between E♭5 (about 622.25Hz) and E5 (about 659.26Hz) — a pitch no piano key produces.

Q9. Does listening to 639Hz improve relationships?

There is no established scientific evidence for that. Research suggests shared musical experience can affect feelings of social connection, but that is a finding about music in general, not about 639Hz. It is most honest to receive it as a symbolic tone for quietly remembering someone.

Q10. Why were Robiraki and Inoko held on the day of the boar?

Because in five-phase thought the boar belongs to water, and water governs fire. A fire lit on that day was believed to be safe from causing a house fire, which is why hearth-opening and kotatsu-opening became tied to it.

Closing | They Grew Cold, So They Came Closer

We tend to read distance as our own failing. I am not good at keeping in touch. I did not say enough. And so we decide a relationship that has cooled is finished. But the Rittou sky says otherwise. The night the stars are clearest is the night that is coldest. Because nothing stands in the way, the heat escapes — and for exactly that reason, what is far away is sharply visible.

Being cold and being connected turned out to be one single fact. And on those nights, people opened the fire. Put away the brazier, laid charcoal in the hearth, handed out rice cakes, took a child by the hand and went out. They grew cold, so they came closer. Every rite at the start of winter is built in that order.

Tonight, if there is someone who has drifted a little, play 639Hz softly and bring them to mind just once. You do not have to write. That you can still remember them is the proof that you can still see them. And tomorrow, if the sky is clear, step outside for five minutes. That cold is the signal that nothing at all stands in between.

References

1. Leonard G. Horowitz & Joseph S. Puleo, Healing Codes for the Biological Apocalypse, Tetrahedron Publishing, 1999. (The source through which the modern Solfeggio numbers were widely popularized; note that its derivation is numerological rather than acoustically verified.)
2. Yoshiro Okada, Koyomi wo Shiru Jiten (An Encyclopedia of the Japanese Calendar), Tokyodo Shuppan. (A reference work on the old calendar, the 24 solar terms, the 72 micro-seasons and traditional annual observances.)
3. National Astronomical Observatory of Japan, ed., Rika Nenpyo (Chronological Scientific Tables), Maruzen (published annually). (Source for the exact dates of the solar terms and climatological normals such as first frost and first snow.)
4. Akihiro Shirai (text) & Kazuhiro Ariga (illustration), Nihon no Shichijuni-kō wo Tanoshimu (Enjoying Japan’s 72 Micro-Seasons), Toho Shuppan, 2012. (An accessible introduction organized by micro-season, covering nature, observances and seasonal foods.)
5. Kunio Yanagita, Nenchū Gyōji Oboegaki (Notes on Annual Observances), Kodansha Gakujutsu Bunko, 1977. (A foundational folklore study covering Inoko, genchō and fire-protection beliefs at the start of winter.)

MuZenCosmos — Where the Cosmos Meets Stillness | They grew cold, so they came closer