# Global Weather – NWS Heat Index Calculator

> Global Weather – NWS Heat Index Calculator is a paid API for AI agents from weather-global.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-21).

Calculates the NWS heat index (feels-like temperature in hot conditions) from air temperature and relative humidity, returning values in both Fahrenheit and Celsius along with an NWS risk category.

## Facts

- Endpoint: GET https://weather-global.x402tookit.com/heat-index?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/global-weather-nws-heat-index-calculator-93348379
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oxlb-txddbzgYkvwpjS7B

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 global-weather-nws-heat-index-calculator-93348379
```

Example prompt: What's the NWS heat index and risk category right now if it's 97°F outside with 85% relative humidity?

## When to prefer this

Use this endpoint when you need the NWS-standard heat index calculation — the official US government formula for feels-like temperature in hot, humid conditions — including the official NWS risk classification (Caution, Extreme Caution, Danger, Extreme Danger). Prefer this over generic weather forecast endpoints when you need a precise, formula-based apparent temperature for safety assessments, health monitoring, or compliance with NWS heat advisory thresholds, without needing real-time location data.

## Known failure modes

- Missing required 'temp' or 'humidity' query parameters returns an error
- Humidity values outside 0–100 range may produce invalid or degraded results
- NWS formula only applies at high temperature and humidity combinations; low conditions may return a degraded or not-applicable result
- Invalid unit value (not F or C) may cause computation failure

## How this service works

NWS heat index (feels-like in heat) from air temperature and relative humidity, in F and C, with the NWS risk category.

## Output

Returns the computed NWS heat index in both Fahrenheit and Celsius, the original input temperature in both units, the humidity percentage used, an NWS risk/danger category label, human-readable guidance, a summary, reasons, and a disclaimer about the calculation method.

## 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": [
      "temp",
      "humidity"
     ],
     "properties": {
      "temp": {
       "type": "number",
       "description": "Air temperature"
      },
      "unit": {
       "type": "string",
       "description": "F (default) or C"
      },
      "humidity": {
       "type": "number",
       "description": "Relative humidity percent, 0 to 100"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "method": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "category": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "guidance": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "heatIndexC": {
       "type": [
        "null",
        "number"
       ]
      },
      "heatIndexF": {
       "type": [
        "null",
        "number"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "humidityPct": {
       "type": [
        "null",
        "number"
       ]
      },
      "temperatureC": {
       "type": [
        "null",
        "number"
       ]
      },
      "temperatureF": {
       "
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/global-weather-nws-heat-index-calculator-93348379/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from weather-global.x402tookit.com](https://www.zero.xyz/host/weather-global.x402tookit.com/llms.txt)