In your project .yml config
---
Name: weather-config
After: weatherforecast/*
---
Injector:
OpenWeatherService:
properties:
key: {your key here}
From your code, call the following. The LocationID will need to be looked up from the openweather site.
Requirements::css('weatherforecast/owfonts/css/owfont-regular.min.css');
$forecast = singleton('OpenWeatherService')->forecastFor($locationID);
The requirements of OpenWeatherMaps mean you must provide attribution on your site for using the service.