Weather app feedback/help

I just finished my weather app and would appreciate some feed back. Also, I have build it on node.js and express, which I’m learning. One problem I would love to solve is how to use ENV variables for the API keys. I have tried dotenv, it works and the ENV variables are accessible in the app.js file, however, I can’t figure out how to access them in external files where I need them: I get the error, ‘process is undefined’. Any feedback and/or help is appreciated.

weather app