# Karte Halowerk UV & Solar Irradiance Forecast

> Karte Halowerk UV & Solar Irradiance Forecast is a paid API for AI agents from karte.halowerk.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Returns hourly CAMS-based UV Index (clear-sky and cloud-adjusted) and surface solar irradiance forecasts for a location in the DACH/Central Europe region.

## Facts

- Endpoint: POST https://karte.halowerk.com/v1/uv-solar
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/karte-halowerk-uv-solar-irradiance-forecast-40132b4a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hR8a-KXgSzoJgqr04ywVj

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability karte-halowerk-uv-solar-irradiance-forecast-40132b4a -d '<json body>'
```

Example prompt: What will the UV index and surface solar irradiance look like hour by hour in Munich (latitude 48.14, longitude 11.58) over the next 72 hours, including both the cloud-adjusted and clear-sky UV values?

## When to prefer this

Choose this endpoint when you need hourly UV Index and solar irradiance forecasts specifically for locations in the DACH region or Central Europe (lat 45–56, lon 5–18), and you want both cloud-adjusted and clear-sky UV values derived from the authoritative CAMS atmospheric model. Prefer it over generic weather APIs when biologically-weighted UV dose rate precision matters (e.g. health, outdoor safety, or PV energy estimation) and when sub-hourly granularity is not required.

## Known failure modes

- Coordinates outside the supported DACH/Central Europe bounding box (lat 45–56, lon 5–18) return an error
- Hours parameter exceeding 120 causes a validation error
- CAMS upstream data unavailability may result in stale or missing forecast values
- Payment failure or insufficient USDC balance blocks the request (x402 protocol)
- Very recent forecast hours may have lower accuracy due to model update latency

## How this service works

Returns an hourly CAMS forecast for UV Index under predicted clouds, clear-sky UV Index and surface solar irradiance. UV Index is derived from the CAMS biologically effective dose rate with the documented factor 40. Solar irradiance is de-accumulated from successive hourly surface-solar-energy fields. Values represent the nearest 0.4 degree model cell, not an on-site pyranometer.

## Output

An array of hourly forecast entries covering up to 120 hours, each containing: the cloud-adjusted UV Index (derived from CAMS biologically effective dose rate × 40), the clear-sky UV Index, and the surface solar irradiance (de-accumulated from successive CAMS hourly surface-solar-energy fields). Values represent the nearest 0.4-degree model grid cell, not a point measurement.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hours": {
   "type": "integer",
   "default": 48,
   "maximum": 120,
   "minimum": 1,
   "description": "Number of hourly forecast values."
  },
  "latitude": {
   "type": "number",
   "maximum": 56,
   "minimum": 45,
   "description": "Latitude inside the cached DACH and Central Europe area."
  },
  "longitude": {
   "type": "number",
   "maximum": 18,
   "minimum": 5,
   "description": "Longitude inside the cached DACH and Central Europe area."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/karte-halowerk-uv-solar-irradiance-forecast-40132b4a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from karte.halowerk.com](https://www.zero.xyz/host/karte.halowerk.com/llms.txt)