The god has not crossed Lake Suwa in eight winters

What this record is, and is not

• 583 winters on record, 1444 to 2026 — the ice is determinate for 567 of them and unsettled for the other 16.
• 八剱神社 has judged this lake since 1443 — with the observation suspended by decree for 21 winters, 1872 to 1892 — the ice for those winters survives in other hands, but the shrine's judgment does not.
• the crossing is recorded per season — only from 1990 — earlier crossings sit in 『諏訪史料叢書』巻17, undigitised.
• The ice-on date survives for 397 of 583 winters — thinnest across 1694–1743, where the ledger recorded only the day the ridge was inspected.

They were listening for it

mean time of day

6:20 in the morning

freeze → crossing, 1444–1682

two to four days

freeze → crossing, 1893–1923

more than twenty

石黒直子 (2001), 地理学評論 74A-7

Then the state stopped it

In 1871 the new Meiji government abolished the viewing ceremony by decree. The entries stop for twenty-one winters. Villagers in 小和田 kept informal notes through the gap, and 八剱神社 petitioned to restore the ceremony in 1893.

「氷は膨張して割れるものだ位に片づけて、こんな迷信はやめた方がいいと観測を中断してしまったのです」

They wrote it off as ice expands and cracks, that is all — decided such superstition had better stop, and broke off the observation.

And the sources do not agree

Two digitisations of this lake's record disagree about nine winters.

The spine every climate paper uses is the Arakawa compilation, which merged every source it could reach without recording which datum came from where. NSIDC also carries the 八剱神社 ledger as its own series. Where the two overlap they do not always agree — and in eight of the nine, the compilation says the lake froze while the shrine's own book says it did not.

All 9 are in the CSV: 1936-37, 1957-58, 1961-62, 1963-64, 1968-69, 1970-71, 1972-73, 1987-88, 1989-90.