Cervia Ironman
Wetsuit Predictor v1.3

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Changelog: 16 Jul 2026 (data review) – Historical data re-verified against the Open-Meteo marine archive: the August mean SST for 2023 (27.8°C), 2024 (29.8°C) and 2025 (27.4°C) all still match source to the decimal, and no race-day reading changed. The API-failure fallback for August SST was refreshed from 26.2°C to 28.3°C (the 2023–25 archive mean) so a dropped live fetch no longer defaults cold – this only affects predictions when the live marine API is unavailable. For context, the current summer is running hot (~29–30°C in mid-July, well above the 2023–25 baseline); the far-out prediction reads this live via Method 7.
v1.3 – Method 7: current-summer anomaly with seasonal persistence (e-folding ~65 days) – the far-out forecast now reacts to how hot the sea is running TODAY vs the 2023–25 same-window baseline, instead of ignoring pre-August observations. Data revision from a source sweep of all Cervia editions (full + 70.3): 2022 corrected to an athlete-reported 21°C wetsuit swim (the race was storm-delayed a day; the old 25.0 was pre-storm satellite – the same wind cold-drop as 2024, whose 21.5 reading the satellite archive confirms against media reports of 23). 2023 satellite value aligned with its cited source. No official 70.3 readings survive online; a 2019 athlete report (21–22°C) conflicts with the previous day's official 24.6 and is excluded pending resolution.
v1.2 – Method 6: physical ocean-model forecast SST (highest weight in race week). Leave-one-out backtest panel; ensemble uncertainty floored at the measured historical error (MAE ~2.2°C weeks out – the probability is now honest about it). Bora/NE-wind cold-tail adjustment via split-normal (a late Bora is how 2024 went mandatory-wetsuit). Per-year August SST from the marine archive (2023–25).
v1.1 – Defaults now target the next upcoming race (2026: Saturday 19 September). Added the 2025 race to the history (satellite SST 25.2°C; official reading not found, flagged as estimated). Estimated years excluded from the measurement-bias calculation. Fixed a variable-ordering bug in the August SST fallback. Prediction maths extracted to a shared engine (js/wetsuit-engine.js) used identically by this page and the ClaudeCoach bot.
v1.0 — Initial release. Five prediction methods for Adriatic water temperature at IRONMAN Italy Cervia — wetsuit or non-wetsuit swim decision.