# SYNTHORA Historical Weather API

> SYNTHORA Historical Weather API is a paid API for AI agents from historical-weather.hergertsynthora.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-11).

Returns verified historical weather data (tmax, tmin, precipitation, max wind) for any location and date from 1940 to ~5 days ago using ERA5 reanalysis data

## Facts

- Endpoint: POST https://historical-weather.hergertsynthora.com/service?utm_source=zero.xyz
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synthora-historical-weather-api-8abea46b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZJRdXvOCZJqQ2wGp7699m

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 synthora-historical-weather-api-8abea46b -d '<json body>'
```

Example prompt: What was the weather like in Berlin on June 6, 1944 — specifically the max and min temperature, precipitation, and max wind speed?

## When to prefer this

Choose this endpoint when you need verified, high-quality historical weather data derived from the ERA5 reanalysis dataset covering dates from 1940 to approximately 5 days ago. It is especially suited for climate-financial backtesting, insurance loss verification, agricultural research, or any use case requiring accurate tmax/tmin, precipitation, and wind data for arbitrary global locations and historical dates. Prefer this over forecast APIs (which only cover future conditions) and over scraped weather archives (which may lack ERA5's scientific rigor and global coverage).

## Known failure modes

- Date out of range (before 1940 or within last 5 days) — returns error or empty result
- Invalid or unrecognized location string — may return error or null result
- Payment not completed — x402 payment required response returned
- Network or upstream ERA5 data unavailability — service timeout or error
- Malformed input string — missing location or date causes processing failure

## How this service works

Live x402 resource on Base. POST /service; payment required responses use x402.

## Output

A JSON object with ok: true, a niche field set to 'historical_weather', a result object containing historical weather variables (tmax, tmin, precipitation, max wind) for the queried location and date, and a cryptographic receipt with an ed25519 signature confirming the paid response.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "string",
   "description": "SYNTHORA historical-weather: verified historical weather for any place and date (1940 → ~5 days ago) from the ERA5 reanalysis — tmax/tmin, precipitation, max wind. For climate-market backtesting and c"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "niche": "historical_weather",
  "result": {},
  "receipt": {
   "alg": "ed25519"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synthora-historical-weather-api-8abea46b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from historical-weather.hergertsynthora.com](https://www.zero.xyz/host/historical-weather.hergertsynthora.com/llms.txt)