Adventures in Machine Learning

Build a Weather App from Scratch in Python: A Step-by-Step Guide

Attention weather enthusiasts and budding developers! Have you ever wished to create your very own weather app that provides the most up-to-date weather information with just a few clicks? Look no further! In this article, we will guide you through the process of building a weather app from scratch.

We will provide you with a step-by-step guide on how to set up the weather app, and build a command line interface. By the end of this article, you’ll have a fully functional weather app that can retrieve the desired weather information in your chosen format.

Setting up the Weather App

Selecting a Weather API

The first step in building a weather app is selecting a weather API to retrieve the weather information. There are multiple weather APIs available, such as OpenWeather, Yahoo Weather, and Weather Underground.

In this article, we will be using OpenWeather API. To use the OpenWeather API, you will need to sign up for an API key.

This is a unique identifier that is used to authenticate and authorize requests to the OpenWeather API. Once you have obtained the API key, you can use it to access the OpenWeather API’s weather data.

Creating the Project Folder Structure

Now that we have selected our weather API and obtained our API key, we can begin setting up the project folder structure. Organizing files in logical directory structures are essential to develop any software project.

Hence, we’ll create the following directories:

– weather

– cli

– models

– services

– tests

– In the ‘weather’ directory, we’ll create our, which will contain the starting point of the program. – The ‘cli’ directory will contain the command line interface logic.

– The ‘models’ directory will hold data models that represent weather data. – The ‘services’ directory will contain classes, functions, or modules that interact with external services, such as API calls.

– Lastly, the ‘tests’ directory will have separate test files for each module. We will also use a ‘.gitignore’ file to ignore files and directories that do not need to be committed to the version control system.

It will prevent keys, secrets, and development configurations from being pushed to a remote repository.

Handling Secrets in Your Code

Our environment configurations such as API keys and secrets should never be included in public repositories. Hence, we will use an INI configuration file to store the secrets of the project.

We’ll create a ‘secrets.ini’ configuration file and place it in the project’s root directory. The configuration file will contain our API key in the following format:



Now we can use the Python in-built ConfigParser library to parse the configuration from the ‘secrets.ini’ file and use it in our program to authorize OpenWeather API calls.

Building the Command-Line Interface

Setting up the Argument Parser

A command-line interface is a critical component of our weather app as it allows users to interact with the program and retrieve weather data. We’ll start by setting up the argument parser module in Python, which allows us to parse input from the command line.

An argument parser will allow us to accept the following arguments:

– City: specifies the name of the city for which we want to retrieve the weather information. – Scale: specifies the desired temperature scale (i.e., Celsius or Fahrenheit).

We’ll use the argparse library to define our CLI arguments and their default values.

Parsing Input Arguments

Once we have set up our arguments, we can parse the command line input and retrieve the user’s desired weather information using our ‘cli’ module. The code in the ‘cli’ module will interact with external APIs and retrieve the necessary weather data to present to the user.

We will then format and present the data to the user in a user-friendly format.


And there you have it! We’ve covered the primary topics of building a weather app from scratch, including selecting a weather API, setting up the project files and directories, handling secrets in your code, and building a command-line interface using argument parsing. Hopefully, this article has provided you with some useful insights on how to create a weather app in Python.

With a little hard work and determination, you can build a weather app that fetches live weather information and presents it in an understandable format for users. Happy coding!

Welcome back! In this article expansion, we will delve deeper into the remaining topics of building a weather app from scratch – retrieving weather information and displaying the output of your Python weather app.

Retrieving Weather Information

Getting Access to a Suitable Weather API

The first step in retrieving weather information is selecting a suitable weather API. In the first topic, we selected OpenWeather API.

Next, we need to establish an API connection with the OpenWeather API.

To get access to weather data, we’ll need to send a request to the OpenWeather API.

Once the API server receives this request, it will process it and send back a response containing the requested data. To send a request to the OpenWeather API, we need to use a request URL.

The URL will include query parameters that help to identify the data we need to retrieve.

Building the API Request URL

We can add query parameters to the request URL to filter the data returned by OpenWeather API. These parameters include the city name, metric, and units, among other parameters.

For instance, to get the weather conditions in Celsius for the city of New York, we would use the following URL:

Here, we’ve passed the ‘q’ parameter, which specifies the city name, the ‘appid’ parameter, which specifies the API key, and the ‘units’ parameter, which specifies the desired temperature scale.

Making an HTTP Request with Python

To send the API request, we can use the requests library. We’ll make a GET request to the OpenWeather API by using the requests.get() method.

If the request was successful, the response object will contain the requested data in JSON format. However, if the request fails, a response error code will be returned.

Handling Exceptions in Your Code

When dealing with external services, such as APIs, there are bound to be connection challenges and errors. To ensure that our program can handle exceptions, we will include a try-except block.

This allows us to handle errors or exceptions that may occur during the API call gracefully. We’ll wrap our API request in a try-except block and catch any connection errors.

In the except block, we will print an error message and exit gracefully, so the program doesn’t crash.

Displaying the Output of Your Python Weather App

Identifying the Relevant Data

Now that we’ve successfully retrieved weather information from the OpenWeather API, we can parse the JSON response to extract the relevant data. To display the output data to the user, we only need to retrieve specific information, such as the weather conditions, temperature, and city name.

Building a Display Function

We’ll build a function to display the output data in an easy-to-understand format. We will use the ‘print’ statement to display main weather conditions, temperature, and the city name.

We can format the output using string formatting in Python.

Adding String Padding to Your Output

To make our output more aesthetically pleasing and readable, we can make use of the ljust() and rjust() functions. These functions can help add padding to our string output, making it look cleaner and more organized.

We can use these functions to ensure all our output strings have the same width regardless of the length of the strings’ content.


In this article expansion, we’ve covered the remaining topics of building a weather app from scratch, including retrieving weather information and displaying the output of your Python weather app. We’ve covered the steps required to establish an API connection with the OpenWeather API and retrieve weather data, handle API connection errors, and parse JSON response to extract relevant data.

Lastly, we’ve covered adding string padding to our output to make our output more organized and readable. With this knowledge, you should be well on your way to building your very own weather app in Python!

Welcome back to our article on building a weather app from scratch in Python.

In this article expansion, we will explore additional topics, including styling the weather app’s output and the conclusion covering finalizing the weather app and the next steps. Styling the Weather App’s Output

Changing Terminal Output Colors

By default, the Python console displays all output in black and white, but we can add some color to our output to make it more visually appealing. We can do this by using ANSI escape codes or by using a Python library called colorama.

Colorama simplifies the process of printing colored text to the console. Using the colorama library, we can set the foreground and background of text printed to our console by applying color codes or names.

Using the following command, we can get different colorama styles:


from colorama import init


print(Fore.RED + ‘Red Text’)


Formatting Weather Types in Different Colors

We can take our output styling a step further by formatting specific weather types in different colors. For instance, we can format “Sunny” in yellow, “Rainy” in blue, and “Cloudy” in grey.

We can achieve this with if/else statements. We will check for the weather type and then use a different color to print the results to the console.

We can also use emojis to provide additional context.

Refactoring Your Code and Adding Emojis

We can refactor our code by using function abstraction, which allows us to separate the code into smaller, more manageable functions. These functions can be tested and improved independently, making it easier to maintain the codebase over time.

We can also add emojis to provide more context to our output. For instance, we can add a sun emoji to the “Sunny” weather type, a cloud emoji to the “Cloudy” type, and a rain emoji to “Rainy” type.

Conclusion and

Next Steps

Finalizing the Weather App

Now that we’ve built the weather app, styled the output, and tested the code to ensure it’s free from errors, we can finalize the project. We can add some documentation to our code that describes how it works and some high-level instructions on how to use it.

We’ll also ensure that all the necessary files are included, such as the INI configuration file and secrets file, so the code will work seamlessly.

Next Steps

While we’ve covered the basics of building a weather app from scratch, many more advanced features can be added to enhance the app’s functionality. We can explore external APIs, create a web interface, or add data visualization charts using libraries like matplotlib or seaborn.

Additionally, we can build a more advanced user interface, allowing users to interact with the app through a mobile app or web application.


In this article expansion, we explored additional topics that can help us build a greater weather app. We discussed styling the weather app’s output using colorama, formatting weather types with different colors, function abstraction, and adding emojis.

Lastly, we discussed finalizing the project and included some next steps for building even more advanced weather apps. With this increased knowledge, we can take our weather project to another level and build more useful, exciting, and enjoyable weather apps.

In this article, we walked through the process of building a weather app from scratch in Python. We started by selecting a suitable weather API, setting up the project folder structure, and handling secrets in the code.

We then built a command-line interface, retrieved weather information, and displayed the output. In the article expansion, we explored additional topics such as styling the weather app’s output, function abstraction, and finalizing the project.

As a take-away, we learned how to retrieve the desired weather information from an API, present it in a user-friendly format, and enhance the app’s functionality. Building a weather app is an exciting project and can be expanded into new, advanced features, making it a worthwhile endeavor for Python developers looking to create useful and enjoyable apps.

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