I know this is old but…my weather wasnt loading. I was trying to use the “forecast” option. Figured out (despite what @Mykle1 said above) that it does work with API keys but I needed to changed weatherEndpoint: in the weather.js file

                apiKey: "YOUR-API-KEY",
                apiSecret: "",
                apiVersion: "2.5",
                apiBase: "https://api.openweathermap.org/data/", // TODO: this should not be part of the weather.js $
                weatherEndpoint: "/forecast",

I had it set to forecast in the config/config.js (below) but that wasnt enough. After I changed the weatherEndpoint, it worked. The

                {
                        module: "weather",
                        position: "bottom_right",
                        config: {
                                type: "forecast"
                        }
                },

Hope this helps someone.