Open-Meteo API
Free, open-source weather API with no API key required, providing hourly and daily forecasts, historical data, and marine/air quality data from multiple numerical weather prediction models.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
No API key for free tier — completely open. Commercial tier uses API key. GDPR-compliant (EU-based). Weather data is not sensitive. Simple, low-risk API.
⚡ Reliability
Best When
You want the simplest possible weather integration for agents with no signup, no API key, and no cost for non-commercial use.
Avoid When
You need commercial SLA guarantees, real-time alerts, or are building a commercial product without licensing.
Use Cases
- • Fetching weather forecasts in agent workflows without API key management
- • Historical weather data retrieval for analytics and backtesting
- • Climate reanalysis data for research and modeling
- • Marine and ocean weather for maritime applications
- • Multi-model ensemble weather data for improved accuracy
Not For
- • Commercial use at scale without commercial license
- • Sub-hourly minute-level resolution data
- • Real-time severe weather alerts
Interface
Authentication
No authentication required for non-commercial use. Commercial API key available for business use with priority support and higher rate limits.
Pricing
Completely free for non-commercial use with no signup. The most agent-friendly weather API for prototyping and personal projects.
Agent Metadata
Known Gotchas
- ⚠ Non-commercial license only - agents deployed in commercial products must use the paid commercial API
- ⚠ Must specify which weather variables you want (temperature_2m, precipitation, etc.) - no default 'give me everything' mode
- ⚠ Timezone parameter required for local time interpretation - missing it returns UTC which may confuse date-based logic
- ⚠ Hourly and daily data in same response are separate arrays requiring careful alignment by index
- ⚠ Historical data endpoint is separate from forecast endpoint with different base URL
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Open-Meteo API.
Scores are editorial opinions as of 2026-03-06.