weather

name	weather
description	Get current weather and forecasts using wttr.in (no install) and Open-Meteo API. No API key required. Use when user asks "what's the weather", "will it rain", "forecast for...", or "weather in <city>".
allowed-tools	["Bash"]
model	haiku
user-invocable	true
when_to_use	When user asks about current weather conditions or forecasts. Triggers: "what's the weather", "weather in <city>", "will it rain today", "forecast for this week", "temperature in...", "should I bring an umbrella".
argument-hint	<city or location> [today|tomorrow|3-day|week]

Weather

Get weather data using curl wttr.in (no install needed) and the Open-Meteo API (free, no key).

Prerequisites

No installation required. curl is available by default on macOS and Linux.

Optionally install jq for cleaner JSON parsing:

brew install jq

Commands

Quick current weather (compact):

curl -s "wttr.in/<city>?format=3"

Full weather report (ASCII art):

curl -s "wttr.in/<city>"

3-day forecast (JSON, for structured output):

curl -s "wttr.in/<city>?format=j1" | jq '.weather[0:3]'

Current conditions only:

curl -s "wttr.in/<city>?format=%C+%t+feels+like+%f+humidity+%h"

Open-Meteo for precise hourly forecast (by coordinates):

curl -s "https://api.open-meteo.com/v1/forecast?latitude=<LAT>&longitude=<LON>&current_weather=true&hourly=temperature_2m,precipitation_probability&forecast_days=3"

Usage Examples

Quick weather check:

curl -s "wttr.in/Tokyo?format=3"
# → Tokyo: ⛅️  +18°C

3-day forecast for Taipei:

curl -s "wttr.in/Taipei?format=j1" | jq '.weather[] | {date: .date, max: .maxtempC, min: .mintempC, description: .hourly[4].weatherDesc[0].value}'

Rain probability today (Open-Meteo):

curl -s "https://api.open-meteo.com/v1/forecast?latitude=25.04&longitude=121.53&hourly=precipitation_probability&forecast_days=1" | jq '.hourly.precipitation_probability'

Current conditions formatted:

curl -s "wttr.in/London?format=%l:+%C,+%t+(feels+%f),+humidity+%h,+wind+%w"

Rules

• Always check if curl is available: which curl (it almost always is)
• No API keys, no accounts — these are free public APIs
• URL-encode city names with spaces: replace spaces with + (e.g., New+York)
• Default to wttr.in for simplicity; use Open-Meteo when user needs hourly breakdown or precise rain probability
• If the user gives a city name, use it directly with wttr.in; if they give a landmark or neighborhood, geocode first via wttr.in (it handles most names)
• Format output in plain text — no raw JSON dumps to the user
• Keep responses concise: current temp, conditions, and forecast summary in 3-5 lines
• Include "feels like" temperature and precipitation chance when relevant