Fetch the forecast

Last time you saw the raw text. Now let’s make it useful.

Goal for this lesson: write a function that returns the forecast as Python data.

Why a function?

A function is a named little machine: you give it what it needs, and it hands back a result. Putting the request in a function means we can reuse it in every later lesson without copying code.

Step 1: Replace your file

Open weather.py and replace everything with this:

import requests

URL = (
    "https://api.open-meteo.com/v1/forecast"
    "?latitude=29.42&longitude=-98.49"
    "&hourly=temperature_2m&temperature_unit=fahrenheit&forecast_days=2&timezone=auto"
)


def get_forecast():
    response = requests.get(URL, timeout=10)
    response.raise_for_status()
    return response.json()


if __name__ == "__main__":
    data = get_forecast()
    print(data.keys())

A few things worth knowing:

• raise_for_status() stops the program with a clear error if the weather service has a problem, instead of letting a bad answer sneak through.
• .json() turns the text into a Python dictionary, which is a collection of labeled values.
• The if __name__ == "__main__": line means “only run this part when I run this file directly.” It lets later files borrow get_forecast without running the print.

Step 2: Run it

python3 weather.py

You should see the labels inside the answer, something like dict_keys(['latitude', 'longitude', ..., 'hourly']). The one we care about is hourly.

Check yourself

Can you see hourly in the list? If so, you have the forecast as real Python data. Take a moment to enjoy that.