OpenWeatherMap
One of the most popular weather APIs with current, forecast, and historical data for any location worldwide.
🔴 Offline · 388 ms
0%
1,000 calls/day, free key, no credit card
API key
Free alternatives (live ranking)
- NOAA National Weather Service — 🟢 Online · Unlimited (US only), no key, no credit card
- 7Timer! — 🟢 Online · Unlimited, no key, no credit card
- Open-Meteo Air Quality — 🟢 Online · 10,000 calls/day, no key, no credit card
Compare OpenWeatherMap with…
- OpenWeatherMap vs NOAA National Weather Service — Unlimited (US only), no key, no credit card
- OpenWeatherMap vs 7Timer! — Unlimited, no key, no credit card
- OpenWeatherMap vs Open-Meteo Air Quality — 10,000 calls/day, no key, no credit card
Paid alternatives
- OWM One Call 3.0 — from $0.0015/call after 1000 free/day
Frequently Asked Questions
Does OpenWeatherMap require an API key?
Yes, OpenWeatherMap requires a free API key. You can sign up via https://openweathermap.org/api.
What is OpenWeatherMap's free tier?
1,000 calls/day, free key, no credit card
Is OpenWeatherMap currently online?
We check OpenWeatherMap every hour. The current status is shown at the top of this page. You can also see the 30-day uptime history in the chart above.
Implementation notes
When to use OpenWeatherMap
OpenWeatherMap suits production apps where you need a single unified API for current conditions, 5-day/3-hour forecasts, and simple air pollution data. The free tier's 1,000 calls/day is tight for high-traffic apps but workable with server-side caching.
Common pitfalls
- The `demo` API key shown in documentation and tutorials returns real data for some endpoints but 401 errors for others. Always register for a real free key — registration takes under two minutes.
- Newly registered API keys are not active immediately. OpenWeatherMap's dashboard states keys can take up to 2 hours to activate; in practice it is usually 10-30 minutes, but first-time users often see 401 errors and assume their key is wrong.
- The free tier covers One Call API 2.5 but not One Call 3.0. One Call 3.0 is metered at $0.0015 per call after 1,000/day even on a free account — you must explicitly opt out of billing or risk unexpected charges if your code calls the 3.0 endpoint.
- Temperature is returned in Kelvin by default. Pass `units=metric` (Celsius) or `units=imperial` (Fahrenheit) to every request; there is no way to set a global account default.
Quick start (bash)
curl "https://api.openweathermap.org/data/2.5/weather?q=London&appid=YOUR_KEY&units=metric"From our monitoring
OpenWeatherMap has the highest average response latency of the weather APIs we monitor, typically 400-700ms. During peak hours (around 13:00-15:00 UTC) we occasionally see spikes to 1,500ms, though the service rarely goes fully down.
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Markdown
[](https://freeapi.watch/openweathermap)HTML
<a href="https://freeapi.watch/openweathermap"><img src="https://freeapi-builder.a10ayassine.workers.dev/badge/openweathermap.svg" alt="OpenWeatherMap Status"/></a>Further reading
- Best Free Weather APIs in 2026: A Data-Driven Comparison — We monitor 15 free weather APIs hourly. Here's which ones are actually reliable, fast, and free-without-friction in 2026.
- Building a Weather App in 2026? Here's the Free API Stack I'd Use — Open-Meteo for forecasts, Nominatim for location lookup, Open-Meteo Air Quality for pollution data. Code snippets and gotchas included.