Need help getting data from API

OK, J Biz , I don't blame you at all on this one. :)

I found two issues here. One is little and easy to fix, and it's not a big deal, now the second one is 100% not your fault. The thing is the API changed since this course was made. (That's how fast technology goes! Imagine if we're actually working with the API, we'd have had to run after a solution).

The first thing I found is in your message constant. The template literal is alright, the only problem, though, is that just as you included current_observation for the weather, the same applies to display_location, since they're both inside the current_observation object.

// So this:
const message = `The weather in ${weather.display_location.full} today is ${weather.current_observation.weather}`;
// (This would tell you "Hey! I can't read full, because it belongs to weather.display_location, which is undefined, in other words: I don't find it".)

// should just be:
const message = `The weather in ${weather.current_observation.display_location.full} today is ${weather.current_observation.weather}`;

The second one is a little more tricky. If you check their docs, they show now there that the query now requires the state or country -slash- the city dot json. Like this:

https://api.wunderground.com/api/Your_Key/conditions/q/CA/San_Francisco.json
//or
http://api.wunderground.com/api/Your_Key/conditions/q/France/Paris.json

There was someone who already commented about this issue here, and honestly the answer there deserves an Oscar, a Pulitzer or a Grammy (you choose!), still, I found a similar solution that I'd like to share with you. NOTE: Anyway, it's clear that you'll have to help yourself with some Front-End-UI-ish stuff to make sure to get the right input (if it's for an end user), or find more specific and ellaborate solutions (if this will only interact with a system), and also, of course, take care of many more scenarios.

Here it is:

// Replace:
// const weatherSearch = process.argv.slice(2).join("_").replace(" ", "_");
// with:
const city = process.argv.slice(2, -1).join("_").replace(" ", "_");
const state = process.argv.slice(-1)[0];
const location = `${state}/${city}`;

// And then, obviously, change your get() url to:
const request = https.get(`https://api.wunderground.com/api/${api.key}/conditions/q/${location}.json`, response => {
// rest of the code here, blah, blah...
}

This way it worked with me, but of course it's still very raw and it can (and should!) be improved a lot, both in modularity (if that's how you call it, notice I didn't make any extra exports to your work, etc.), and in functionality. So you still have plenty of work to do. :) Hope at least that helps you go on with it. Let me know if it worked to you too!