This kō's name comes from an old cosmology in which heaven's energy rises and earth's energy withdraws downward, and the two stop meeting — 閉塞, "sealed shut." Spring through autumn were understood as the season when sky and ground stayed in exchange with each other; winter is the recess. Practically, what that describes is the low, heavy, grey cloud cover that now settles over much of the country, especially the Sea of Japan coast, where it's specifically named 雪曇り (yukigumori, "snow-cloud") — a sky that looks permanently on the verge of snow, whether or not it actually falls that day.
大雪 (Taisetsu) itself simply means "heavy snow," the point in the solar calendar where snowfall is expected to turn serious in the mountains and along the Sea of Japan coast, even where the Pacific side stays comparatively dry and merely cold.
Approaching true peak — 寒鰤 (kanburi), the richest and most prized stretch of the buri season, is close now.
In excellent season; its milt (白子, shirako) is a genuine winter delicacy, silky when lightly grilled or poached.
In full season, its fragrance doing more work in a winter kitchen than almost anything else available now.
Late-season varieties are dense, sweet, and keep well — good to have on hand through the cold months.
At full sweetness, central to the season's nabe cooking.
Still in good season, its bitterness a good counterweight to a rich broth.
Sweet and deep-flavored now, excellent long-simmered in oden.
Senryō and manryō are grown almost entirely for their bright red winter berries rather than any flower, and both start appearing in New Year arrangements right around now. Old custom paired them with ariboshi (a third red-berried plant, its name meaning roughly "always present") into the pun 千両万両有り通し — "a thousand in gold, ten thousand in gold, and may it always be so" — a fairly blunt wish for money that never runs out, dressed up as a houseplant.
Traditionally observed December 8th in old Edo and December 13th in Kamigata (the Kyoto-Osaka region) — Edo-period almanacs marked the 13th as an 鬼 (oni, "demon") day in a 27-day lunar-mansion cycle, and, oddly, a demon day was considered auspicious for everything except weddings, which made it a fitting date to start welcoming the year's incoming deity. The day's first task is 煤払い (susuharai), a thorough top-to-bottom soot-and-dust cleaning of the whole house — originally literal, from centuries of hearth and lamp soot accumulating on ceiling beams, and now closer to a ritual deep clean that doubles as spiritual purification ahead of the New Year's kami.
"Snow-cloud sky" — A winter season word for the low, uniformly grey cloud cover — heavy, still, not yet actively snowing — most associated with the Sea of Japan coast at exactly this point in the calendar, where it can persist for days without a clear break.
閉塞 pairs two characters that both mean roughly "to close off" or "obstruct" — 閉 (a gate shutting) and 塞 (a border fortress blocking passage) — doubled up for emphasis rather than adding new meaning. The name isn't describing weather directly at all; it's describing a cosmological state (heaven and earth no longer exchanging their respective energies) that weather happens to be the visible symptom of.
A full top-to-bottom clean is easier tackled over several unhurried days in early Taisetsu than crammed into the last chaotic week before New Year.
The characteristic flat grey overcast is worth noticing on its own terms — a sky that can hold for days without resolving into actual snowfall.
"Sleeping on the road, I happened to see it — this fleeting world's soot-sweeping."
Garden centers and flower shops carry both through December specifically for New Year arrangements — worth picking up early rather than the week prices peak.
Buri keeps improving through Taisetsu; patience now is rewarded with noticeably richer fish by the solstice.
Bashō watches other households doing their year-end cleaning from outside it entirely — a traveler with no house of his own to sweep, observing a ritual of settling in and starting fresh that has nothing to do with him this particular winter. There's no self-pity in it, just clear-eyed noticing. Is there a seasonal ritual around you right now that isn't quite yours to take part in — and what does it look like to watch it well, rather than resent not joining?