How to store weather forecast data for fast time-series APIs

Thanks for sharing the info about the Open-Meteo APIs.

As you mentioned PostgreSQL I thought I'd share that maybe between PostGIS and TimescaleDB extensions you might get much closer to a relational database that overcomes some of those drawbacks you list.

Transparency: I work for Timescale. There's lots of no-charge resources if you did want to explore, and the software itself is offered under a Community license (free software, open code).