Static JSON API

Base URL

https://coldfront.wi7.net/api/v1/

Current state

Data version Oct 13, 2026, issued on Oct 13, 2026, model: ensemble-dyn-season-holiday. The forecast covers 17 regions.

Files

Region IDs

Fields of the region files

The fields follow the TypeScript interfaces of the forecast-core package. These interfaces are the binding description.

Quantiles and bands

Each forecast is a set of quantiles. q50 is the median. The 50 % band runs from q25 to q75, the 80 % band from q10 to q90. The quantiles are sorted in ascending order. The bands describe the uncertainty of the model; they are not guaranteed limits.

Activity levels

The index is the median of the forecast divided by the median of the seasonal norm for the target week. From 1.25 the level is elevated, from 1.75 it is high, below that it is normal. The thresholds are start values and have not been validated empirically.

Examples

curl -s "https://coldfront.wi7.net/api/v1/index.json"

const res = await fetch("https://coldfront.wi7.net/api/v1/regions/de-sn.json");
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const forecast = await res.json();
for (const h of forecast.horizons) {
  console.log(h.iso_week, h.q25, h.q50, h.q75);
}

{
  "h": 1,
  "iso_week": "YYYY-Www",
  "q10": 0,
  "q25": 0,
  "q50": 0,
  "q75": 0,
  "q90": 0,
  "index": 0,
  "level": "normal"
}

Browser access (CORS)

The files are served with the header Access-Control-Allow-Origin: *. Browser applications on other origins can therefore read them directly.

Versioning

Every forecast file carries schema_version. The current version is 1. Check this value before you process the file.

Reuse and attribution

No licence has been chosen for the program code yet. The data keep the licence of their source; details are under Data & sources. Forecasts are our own calculations based on this data and must be attributed accordingly. Use the following attribution text:

Quelle: Robert Koch-Institut, Umweltbundesamt, Deutscher Wetterdienst; eigene Berechnung