Have you tried a http request
Try this add your api key to url in http request node.
[{"id":"dc0a24d356999705","type":"inject","z":"d1395164b4eec73e","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":640,"y":7860,"wires":[["bbb049edd2f2ea79"]]},{"id":"bbb049edd2f2ea79","type":"http request","z":"d1395164b4eec73e","name":"","method":"GET","ret":"obj","paytoqs":"ignore","url":"api.openweathermap.org/data/2.5/forecast?lat=44.34&lon=10.99&appid={API key}","tls":"","persist":false,"proxy":"","insecureHTTPParser":false,"authType":"","senderr":false,"headers":[],"x":810,"y":7860,"wires":[["49ca1933244b103b"]]},{"id":"49ca1933244b103b","type":"debug","z":"d1395164b4eec73e","name":"debug 2488","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":990,"y":7860,"wires":[]}]
Docs for 5 day forcast api