Tutorial: Open-Meteo (Weather)

Environment

Data source: Open-Meteo, NWS

Overview

Open-Meteo (Weather) wraps Open-Meteo, NWS, handling authentication, pagination, and rate limits for you. This tutorial covers all 8 tools with working code examples you can copy and run.

Prerequisites

Sign up at https://context.gnist.ai/signup for a free API key (100 calls/day).
Choose your integration method: MCP protocol or REST API.

Connect via MCP

Add to your MCP client config (Claude Desktop, Cursor, etc.):

MCP Config

{
  "mcpServers": {
    "gnist-open-meteo": {
      "url": "https://context.gnist.ai/mcp/open-meteo/",
      "headers": {
        "Gnist-API-Key": "YOUR_API_KEY"
      }
    }
  }
}

Tools (8)

`geocode_location`

Search for a city or place name and return matching coordinates. Use this tool first to convert a place name into latitude/longitude coordinates, then pass those coordinates to the weather, air quality, or marine forecast tools. Returns matching locations with name, coordinates, country, population, and timezone.

Parameter	Type	Required	Description
`name`	string	required	City or place name to search for (e.g. "Oslo", "New York", "Tokyo").
`count`	integer	optional	Maximum number of results to return (1-100). Default 5. (default: `5`)
`language`	string	optional	Response language as ISO 639-1 code (e.g. 'en', 'de', 'fr'). Default 'en'. (default: `en`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "geocode_location", "arguments": {"name": "Oslo"}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'name': 'Oslo'}, 'name': 'geocode_location'}},
)
print(resp.json())

`get_current_weather`

Get current weather conditions at a location. Returns current temperature, humidity, wind, precipitation, and description. Weather descriptions follow the WMO Weather Interpretation Code standard.

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the location (-90 to 90).
`lon`	number	required	Longitude of the location (-180 to 180).
`units`	string	optional	Unit system: "metric" (C, m/s, mm) or "imperial" (F, mph, inch). (default: `metric`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_current_weather", "arguments": {"lat": 59.91, "lon": 10.75}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'lat': 59.91, 'lon': 10.75},
            'name': 'get_current_weather'}},
)
print(resp.json())

`get_weather_forecast`

Get hourly weather forecast for a location. Returns hourly forecast entries with temperature, precipitation probability, wind, and weather description for each hour. Up to 7 days (168 hours).

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the location (-90 to 90).
`lon`	number	required	Longitude of the location (-180 to 180).
`hours`	integer	optional	Number of hours to forecast (1-168, default 24). (default: `24`)
`units`	string	optional	Unit system: "metric" (C, m/s, mm) or "imperial" (F, mph, inch). (default: `metric`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_weather_forecast", "arguments": {"lat": 59.91, "lon": 10.75}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'lat': 59.91, 'lon': 10.75},
            'name': 'get_weather_forecast'}},
)
print(resp.json())

`get_alerts`

Get active severe weather alerts for a location. Currently covers the United States via the National Weather Service (NWS) API. Returns an empty list for non-US coordinates.

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the location (-90 to 90).
`lon`	number	required	Longitude of the location (-180 to 180).

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_alerts", "arguments": {"lat": 59.91, "lon": 10.75}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'lat': 59.91, 'lon': 10.75}, 'name': 'get_alerts'}},
)
print(resp.json())

`get_historical_weather`

Get historical weather data for a location and date range. Draws from the ERA5 climate reanalysis archive, covering 1940-01-01 to approximately 5 days before the current date. Returns daily summaries with max/min/mean temperature, precipitation, and wind speed.

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the location (-90 to 90).
`lon`	number	required	Longitude of the location (-180 to 180).
`start_date`	string	required	Start of the date range, format YYYY-MM-DD (earliest: 1940-01-01).
`end_date`	string	required	End of the date range, format YYYY-MM-DD (latest: ~5 days ago).
`units`	string	optional	Unit system: "metric" (C, m/s, mm) or "imperial" (F, mph, inch). (default: `metric`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_historical_weather", "arguments": {"lat": 59.91, "lon": 10.75, "start_date": "2025-01-15", "end_date": "2025-01-15"}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'end_date': '2025-01-15',
                          'lat': 59.91,
                          'lon': 10.75,
                          'start_date': '2025-01-15'},
            'name': 'get_historical_weather'}},
)
print(resp.json())

`get_air_quality`

Get air quality forecast for a location. Returns hourly air quality data including European AQI, US AQI, PM2.5, PM10, carbon monoxide, nitrogen dioxide, sulphur dioxide, and ozone. AQI scales: - European AQI: 0-20 Good, 20-40 Fair, 40-60 Moderate, 60-80 Poor, 80-100 Very Poor, 100+ Extremely Poor - US AQI: 0-50 Good, 51-100 Moderate, 101-150 Unhealthy (sensitive), 151-200 Unhealthy, 201-300 Very Unhealthy

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the location (-90 to 90).
`lon`	number	required	Longitude of the location (-180 to 180).
`hours`	integer	optional	Number of hours to forecast (1-120, default 24). (default: `24`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_air_quality", "arguments": {"lat": 59.91, "lon": 10.75}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'lat': 59.91, 'lon': 10.75},
            'name': 'get_air_quality'}},
)
print(resp.json())

`get_marine_forecast`

Get marine/ocean forecast for a coastal location. Returns hourly wave data including total wave height, direction, and period, as well as separate wind-wave and swell components. Best for coastal and offshore locations; inland locations may return null values.

Parameter	Type	Required	Description
`lat`	number	required	Latitude of the coastal location (-90 to 90).
`lon`	number	required	Longitude of the coastal location (-180 to 180).
`hours`	integer	optional	Number of hours to forecast (1-168, default 24). (default: `24`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "get_marine_forecast", "arguments": {"lat": 59.91, "lon": 10.75}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'lat': 59.91, 'lon': 10.75},
            'name': 'get_marine_forecast'}},
)
print(resp.json())

`report_feedback`

Report a bug, feature request, or general feedback for this data source. Use this when something doesn't work as expected, when you'd like a new feature, or when you have suggestions for improvement. Args: feedback: Describe the issue or suggestion. feedback_type: One of 'bug', 'feature_request', or 'general'.

Parameter	Type	Required	Description
`feedback`	string	required
`feedback_type`	string	optional	(default: `general`)

curl -X POST "https://context.gnist.ai/mcp/open-meteo/" \
  -H "Content-Type: application/json" \
  -H "Gnist-API-Key: YOUR_API_KEY" \
  -d '{"jsonrpc": "2.0", "method": "tools/call", "id": 1, "params": {"name": "report_feedback", "arguments": {"feedback": "example"}}}'

import httpx

resp = httpx.post(
    "https://context.gnist.ai/mcp/open-meteo/",
    headers={"Gnist-API-Key": "YOUR_API_KEY"},
    json={'id': 1,
 'jsonrpc': '2.0',
 'method': 'tools/call',
 'params': {'arguments': {'feedback': 'example'}, 'name': 'report_feedback'}},
)
print(resp.json())

Common Patterns

Date range filtering
Use date range parameters to narrow results to a specific time window. Dates are typically in YYYY-MM-DD format.

FAQ

What data does Open-Meteo (Weather) provide?

Current weather, forecasts, historical data, and severe weather alerts. It exposes 8 tools: geocode_location, get_current_weather, get_weather_forecast, get_alerts, get_historical_weather, get_air_quality, get_marine_forecast, report_feedback.

What do I need to get started?

A Gnist API key (free tier: 100 calls/day). Sign up at https://context.gnist.ai/signup.

What format does the Open-Meteo (Weather) API return?

JSON, via either MCP protocol (JSON-RPC 2.0) or REST API.

Next Steps

Interactive Playground

Try tools in your browser — no setup required.

Full Reference

Complete docs for all 8 tools.

Getting Started with Open-Meteo (Weather)