Static replay of a past cold spell — this is not a live alerting service and it is not monitoring anything. Coldsnap is a FastAPI app; Cloudflare Pages serves static files only, so what is published here is the project's own offline dashboard, pre-rendered. The scrubber steps hour by hour through the real 1–12 January 2025 UK cold spell (Open-Meteo ERA5 reanalysis), assessing three fictional patients against it. Every tier you see is a historical what-if for January 2025, not a statement about the weather now or about anyone real.

Two things are switched off because they need the Python backend: “Fetch live data now” (the live mode calls four real APIs) and the feedback buttons (they write to the server to move a patient's band). The multi-condition panel below is therefore in FIXTURE mode, and the app labels every source that way — in that mode it is designed to report UNKNOWN rather than CLEAR, because “we checked and there is nothing” and “we could not check” are opposites. To use the live paths, run the project locally (./run.sh live).

Weather data: Open-Meteo — ERA5 archive and forecast, CC BY 4.0, attribution to Copernicus/ECMWF; the free tier is non-commercial and this is a portfolio demonstration. Air-quality fixtures via Open-Meteo (CAMS) and London Air (Imperial College ERG); warnings via the Met Office public RSS.

This is not medical advice and not an emergency service. It does not replace clinical judgement or your own pain plan. If your pain is severe, you are breathless, have chest pain or a fever, call 999 or NHS 111 now. Thresholds shown are illustrative engineering defaults, not clinically validated values, and the three patients are fictional.