Fetch weather data for the dataset period plus forecast horizon.
Creates a weather DataFrame using the Open-Meteo API with optional caching. Caching is controlled solely by the cache_home argument: when a path is provided the service reads from / writes to a parquet cache file inside that directory; when None (the default) no caching is performed.
Optional path to cache directory. When provided, fetched weather data is cached in <cache_home>/weather_cache.parquet. When None (default), no caching is performed.