weather

A command-line tool that provides current weather conditions and forecasts for a specified city, region, or airport. It uses wttr.in or Open-Meteo and does not require an API key.

In plain words
What is it for?
Use it to check current conditions, temperatures, rain, wind, and forecasts for today, tomorrow, or the coming week.
Why use it?
It gives an agent a quick way to answer location-based weather questions without setting up a paid weather service.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/understudy-ai/understudy/weather
Any agent
npx skills add understudy-ai/understudy --skill weather
Clone the repo
git clone --depth 1 https://github.com/understudy-ai/understudy

Made for: Claude Code, Codex.

Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 662 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin 97% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00055 $0.00662
Opus 5 $0.00028 $0.00331
Sonnet 5 $0.00011 $0.00132
Haiku 4.5 $0.00006 $0.00066

Measured 3d ago against content hash c77dd5784214, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

weather scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

metadata: { "understudy": { "emoji": "🌤️", "requires": { "bins": ["curl"] } } }
Origin

This is a copy

97% identical to weather — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/weather/SKILL.md · 113 lines

What it actually says

Weather Skill

Get current weather conditions and forecasts.

When to Use

USE this skill when:

  • "What's the weather?"
  • "Will it rain today/tomorrow?"
  • "Temperature in [city]"
  • "Weather forecast for the week"
  • Travel planning weather checks

When NOT to Use

DON'T use this skill when:

  • Historical weather data → use weather archives/APIs
  • Climate analysis or trends → use specialized data sources
  • Hyper-local microclimate data → use local sensors
  • Severe weather alerts → check official NWS sources
  • Aviation/marine weather → use specialized services (METAR, etc.)

Location

Always include a city, region, or airport code in weather queries.

Commands

Current Weather

# One-line summary
curl "wttr.in/London?format=3"

# Detailed current conditions
curl "wttr.in/London?0"

# Specific city
curl "wttr.in/New+York?format=3"

Forecasts

# 3-day forecast
curl "wttr.in/London"

# Week forecast
curl "wttr.in/London?format=v2"

# Specific day (0=today, 1=tomorrow, 2=day after)
curl "wttr.in/London?1"

Format Options

# One-liner
curl "wttr.in/London?format=%l:+%c+%t+%w"

# JSON output
curl "wttr.in/London?format=j1"

# PNG image
curl "wttr.in/London.png"

Format Codes

  • %c — Weather condition emoji
  • %t — Temperature
  • %f — "Feels like"
  • %w — Wind
  • %h — Humidity
  • %p — Precipitation
  • %l — Location

Quick Responses

"What's the weather?"

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

"Will it rain?"

curl -s "wttr.in/London?format=%l:+%c+%p"

"Weekend forecast"

curl "wttr.in/London?format=v2"

Notes

  • No API key needed (uses wttr.in)
  • Rate limited; don't spam requests
  • Works for most global cities
  • Supports airport codes: curl wttr.in/ORD
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 113 lines · 55 tokens per session scan A c77dd5784214

Subscribe to this mod's changes

weather is a skill published in the GitHub repository understudy-ai/understudy (456 stars, last pushed 2mo ago), licensed MIT. It adds 55 tokens to every session and 662 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 97% identical to weather, differing in 6 lines, and is treated as a copy.