FMI Open Data API vs Open-Meteo Ensemble API

Two free Weather APIs compared on access, reliability and developer ratings, using data from our daily health checks.

The verdict

Choose FMI Open Data API if its data fits your use case better; on access and reliability it's level with Open-Meteo Ensemble API.
Choose Open-Meteo Ensemble API if you want faster responses.

	FMI Open Data API	Open-Meteo Ensemble API
What it does	Finnish weather, sea, climate and radar observations via open WFS.	Weather ensemble forecasts from multiple models.
Provider	Finnish Meteorological Institute	Open-Meteo.com
API key	Not needed	Not needed
HTTPS	Yes	Yes
CORS (browser calls)	Yes	Yes
Status today	Online · 1444 ms	Online · 523 ms
Uptime (30 days)	Up	Up
Developer rating	Not rated yet	Not rated yet
Price	Free / free tier	Free / free tier

Finnish weather, sea, climate and radar observations via open WFS.

The majority of the Finnish Meteorological Institute's data is available as open data. The data is in a machine-readable, digital format.

Strengths

Weather ensemble forecasts from multiple models.

Ensemble weather forecasts from ICON, GFS, ECMWF, GEM and more. Access individual ensemble members for probabilistic forecasting via a free JSON API.

Strengths

Prototyping or a tutorial? Pick the one that needs no API key (both qualify).
Calling from a web page? You need CORS. Otherwise route requests through your own server or a serverless function.
Going to production? Favour HTTPS, a strong uptime record and a provider with clear rate limits and terms. Check each API's docs before you commit.
Still unsure? Both are free to try: send one request to each and compare the data you get back.

Neither needs an API key; you can call both straight away.