# Weather Observed Temperatures for Prediction Markets (Kalshi & Polymarket)

> Weather Observed Temperatures for Prediction Markets (Kalshi & Polymarket) is a paid API for AI agents from weather-x402.linholiday.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Returns observed temperature readings (max/min/latest) for a given ICAO weather station, structured for Kalshi and Polymarket temperature market settlement.

## Facts

- Endpoint: GET https://weather-x402.linholiday.workers.dev/observed?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/weather-observed-temperatures-for-prediction-markets-kalshi-polymarket-90db0ef6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_n8zPjDDDPX3Of3q6gZoXR

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 weather-observed-temperatures-for-prediction-markets-kalshi-polymarket-90db0ef6
```

Example prompt: What were the observed high and low temperatures at KNYC today — I need the Kalshi climate day window values in both Celsius and Fahrenheit to check my temperature market position.

## When to prefer this

Use this endpoint when you need structured, prediction-market-ready observed temperature data (max/min/latest) from METAR reports at a specific ICAO station, particularly for settling Kalshi or Polymarket temperature contracts. Prefer this over generic weather APIs when you need the exact Kalshi climate day window format with whole-number Fahrenheit values, or when you need micropayment-compatible access (x402/USDC) without API key registration. Choose it over forecast APIs when you need historical or current-day observed actuals, not predictions.

## Known failure modes

- Invalid or unknown ICAO station ID returns an error or empty windows
- Station not reporting — no recent METAR data may result in zero observations or missing best_estimate
- Endpoint requires payment via x402 (0.01-0.02 USDC on Base/eip155:8453); unpaid requests return HTTP 402
- Data may lag real-time by up to one observation cycle (~1 hour) for recently updated stations
- Station IDs must be in ICAO format (e.g. KMDW, not ORD); IATA codes will fail

## How this service works

Paid calls cost 0.01-0.02 USDC on eip155:8453 via x402 (exact scheme). Free: /stations, /preview/*, /health, /, /openapi.json, /llms.txt, /.well-known/x402.

## Output

Returns a JSON object containing the ICAO station ID, local date, and a 'windows' object with a 'kalshi_climate_day' entry that includes: number of observations, latest temperature reading (°C and °F with timestamp), best-estimate max and min temperatures (°C, °F, and whole-number °F), and the raw max and min across all METAR reports (with timestamps and report types).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "station"
     ],
     "properties": {
      "station": {
       "type": "string",
       "description": "Settlement station ICAO id, e.g. KMDW, KLGA, EGLC"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "station": "KNYC",
  "windows": {
   "kalshi_climate_day": {
    "n_obs": 10,
    "latest": {
     "c": 11.1,
     "f": 52,
     "time": "2026-10-21T13:51:00.000Z"
    },
    "best_estimate": {
     "max": {
      "c": 12.2,
      "f": 54,
      "f_whole": 54
     },
     "min": {
      "c": 8.3,
      "f": 46.9,
      "f_whole": 47
     }
    },
    "max_all_reports": {
     "c": 11.1,
     "f": 52,
     "time": "2026-10-21T13:51:00.000Z",
     "type": "METAR"
    },
    "min_all_reports": {
     "c": 8.3,
     "f": 46.9,
     "time": "2026-10-21T09:51:00.000Z",
     "type": "METAR"
    }
   }
  },
  "local_date": "2026-10-21"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/weather-observed-temperatures-for-prediction-markets-kalshi-polymarket-90db0ef6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from weather-x402.linholiday.workers.dev](https://www.zero.xyz/host/weather-x402.linholiday.workers.dev/llms.txt)