Building a Weather Forecast App with Claude Code and API Integration

Building a Weather Forecast App with Claude Code and API Integration

In previous articles, I built projects up to a price monitoring tool. This time, I’m taking on “API integration.” I built a weather forecast app that fetches real-time weather data from an external service’s API.

What We’re Building: A Weather Forecast App

Key Features

• Current weather display: Shows temperature, humidity, and weather conditions
• Weekly forecast: Lists the 7-day weather forecast at a glance
• Multi-city support: Search weather for any city you like
• Visual presentation: Weather icons and temperature graphs
• API integration: Fetches the latest data from the OpenWeatherMap API

Conversation with Claude Code

I asked Claude Code: “Build an app that displays the weather forecast. I want it to fetch real-time weather information using an API.”

Claude Code suggested an implementation using the OpenWeatherMap API:

• How to set up the API key
• Making API calls with the requests library
• Parsing JSON responses
• Temperature unit conversion (Kelvin to Celsius)

Implementation Walkthrough

1. City Name Input

Enter the name of the city you want to check, and the app fetches the weather data for that location.

2. Current Weather Display

The data retrieved from the API is formatted and displayed in an easy-to-read layout.

Information shown:

• Weather conditions (sunny, cloudy, rainy, etc.)
• Temperature (current / high / low)
• Humidity
• Wind speed

3. Weekly Forecast

You can also view the 7-day weather forecast in a list format.

4. Temperature Trend Graph

Using matplotlib, the weekly temperature changes are visualized in a graph.

Learning How to Use APIs

Getting an API Key

You sign up for the OpenWeatherMap free plan and obtain an API key. Claude Code even walked me through the registration steps.

API Call Basics

Using the requests library, calling an API is straightforward:

• Send a GET request with parameters appended to the URL
• Handle the JSON response as a Python dictionary
• Error handling (e.g., when a city is not found)

Impressions After Using It

What Went Well

• Real-time data: Always up-to-date weather information
• API learning: Gained practical API integration skills
• Visually intuitive: Graphs and icons make it easy to understand
• Multi-city support: Can check weather for cities around the world

Room for Improvement

• Make the weather icons more visually appealing
• Add notification features (e.g., when rain is expected)
• Save favorite locations
• Add hourly detailed forecasts

Summary

Using Claude Code, I was able to build a weather forecast app with API integration.

I learned that by leveraging external APIs, you can add all sorts of capabilities to your own apps. Beyond OpenWeatherMap, there are news APIs, translation APIs, map APIs, and many more — I’m looking forward to exploring them in future projects.

Next time, I plan to build on this app and turn it into something even more practical.

See you in the next article!