The Sake Brewing Calendar

The whole calendar follows from one fact: before refrigeration, temperature was something you found, not something you set. Brewers found it in winter. From the 17th century onward, kanzukuri — brewing only in the cold months — became the mainstream method precisely because the season did the cooling for them.

The cold helps in two ways at once. It keeps the fermenting mash (moromi) slow and steady, which builds depth and the ginjo-style aromas a fast warm ferment would burn off. And the dry winter air holds back the contaminating bacteria that thrive in heat — the same bacteria that spoiled summer-brewed sake.

This is a local-climate adaptation, and it sits inside a craft UNESCO now recognizes. The 2024 inscription describes brewers who “oversee the process to make sure the mould grows in optimal conditions, adjusting the temperature and humidity as needed” — the same instinct for working with the environment, scaled from the koji room to the whole calendar. What UNESCO actually inscribed covers that craft in full.

Shinshu (新酒, “new sake”) simply means sake from the current brewing year, made from the latest rice harvest. Releases from roughly November through March carry that name. It is the calendar announcing itself.

Shiboritate (しぼりたて) is the headline version. Most sake rests six months or more after pressing; shiboritate skips the wait and goes straight to the bottle. With little or no pasteurization, it keeps a fresh, slightly cloudy, almost crackling character that mellows fast — so it is meant to be drunk young.

If you want to understand why “unpasteurized” matters here — what hi-ire does and why nama tastes different — that is a step in the brewing process, not the calendar.

Hiyaoroshi (冷やおろし) is what the quiet summer is for. The same sake pressed in winter rests through the heat, its sharpness softening into rounder umami. Because it is pasteurized only once — in spring, not again before sale — it keeps a delicate balance the second heating would flatten.

The name is literal: hiya (cold) and oroshi (to draw down). When the sake had cooled to match the autumn air outside, it was drawn from the storage tubs and shipped. It lands from around September; the Japan Sake & Shochu Makers Association marks 9 September — the Chrysanthemum Festival — as the season's first day, though shops often start earlier.

Akiagari (秋上がり) is the close cousin, and the words are often swapped. Strictly, akiagari describes the state— spring-pressed sake that has “risen” in flavor over summer — and the bottles labeled this way are usually pasteurized a second time before autumn shipping, where hiyaoroshi is not. Mellower and rounder either way.

You will see sake dated by BY, the brewing year. Japan's National Tax Agency sets it from 1 July to 30 June, so a bottle marked “BY2025” was brewed in the season starting July 2025 — which in practice means the winter that followed. It is a tax-and-accounting line, not a tasting one.

The cultural anchor is different. The Japan Sake & Shochu Makers Association named 1 October “Sake Day,” a nod to the old brewing year that once began that month — right as kanzukuri was about to start. The calendar has shifted on paper; the rhythm of the season has not.