Project: Weather Data Fetcher in Python0%

Project: Weather Data Fetcher in Python

Intermediate8 min read•Updated: 2026-10-01

Project: Weather Data Fetcher

In this hands-on project, we will apply the HTTP networking concepts covered throughout this chapter—HTTP Requests, Query Parameters, JSON Parsing, and Network Exception Handling—to build a functional, real-time Command-Line Weather Data Fetcher.

We will connect to the open, free Open-Meteo API (which requires zero API keys or credit cards) to look up city coordinates and fetch current meteorological telemetry.

1. System Architecture & API Endpoints

Our weather application performs a two-stage API pipeline:

1
Geocoding API: Resolves a user's textual city query (e.g. "Mumbai" or "London") into exact latitude and longitude coordinates.

Endpoint: https://geocoding-api.open-meteo.com/v1/search?name={city}&count=1

1
Forecast Weather API: Fetches current weather telemetry for those coordinates.

Endpoint: https://api.open-meteo.com/v1/forecast?latitude={lat}&longitude={lng}&current_weather=true

1
Data Translation Layer: Maps numerical WMO weather codes (e.g. Code 0 = "Clear Sky", Code 61 = "Slight Rain") to user-friendly status descriptions.

2. Complete Application Code

Visual Architecture & Process Flow

How data and code flow step-by-step

Flowchart

Step 1

def get_coordinates

self, city_name: str

Step 2

Optional[Tuple[float, float, str, str]]:

3. Sample Execution Simulation

1==================================================
2      REAL-TIME GLOBAL WEATHER DASHBOARD
3==================================================
4 
5Enter city name (or 'quit' to exit): New Delhi
6 
7Searching coordinates for 'New Delhi'...
8 
9==================================================
10       WEATHER REPORT: NEW DELHI, INDIA ☀️
11==================================================
12 Coordinates       : 28.61°N, 77.21°E
13 Condition         : Clear sky
14 Temperature       : 31.4°C (88.5°F)
15 Wind Speed        : 8.2 km/h
16 Wind Direction    : 295°
17==================================================
18 
19Enter city name (or 'quit' to exit): London
20 
21Searching coordinates for 'London'...
22 
23==================================================
24       WEATHER REPORT: LONDON, UNITED KINGDOM 🌧️
25==================================================
26 Coordinates       : 51.51°N, -0.13°E
27 Condition         : Slight rain
28 Temperature       : 14.2°C (57.6°F)
29 Wind Speed        : 19.8 km/h
30 Wind Direction    : 210°
31==================================================
32 
33Enter city name (or 'quit' to exit): quit
34Thank you for using the Weather Dashboard. Stay safe!

⚠️ Common Intermediate Mistakes & Gotchas

1. Unhandled Network Disconnection

Network drops raise requests.exceptions.ConnectionError. Always wrap API calls in a try-except block targeting requests.exceptions.RequestException.

2. Assuming City Names Are Always Valid

Handle 404 responses gracefully by informing the user that the city was not found rather than letting the application crash with a traceback.

💻 Try It Yourself: Extension Challenge - Temperature Unit Switch

Challenge

Extend the Weather Data Fetcher to accept a command-line flag (--unit C or --unit F) that converts temperatures between Celsius and Fahrenheit.

Complete Solution

1def convert_temp(celsius_temp: float, unit: str = "C") -> str:
2    if unit.upper() == "F":
3        fahrenheit = (celsius_temp * 9/5) + 32
4        return f"{fahrenheit:.1f}°F"
5    return f"{celsius_temp:.1f}°C"
6 
7# Test conversion
8print("28°C in Fahrenheit:", convert_temp(28.0, "F"))
9print("28°C in Celsius:", convert_temp(28.0, "C"))

Expected Output

128°C in Fahrenheit: 82.4°F
228°C in Celsius: 28.0°C

Interactive Quiz• Knowledge Check

Practice Quiz

Question 1

In this project, what is the role of the Geocoding API step?

Question 2

Why is self.session = requests.Session() instantiated inside the WeatherFetcher constructor?

Question 3

What does WEATHER_CODES.get(code, ("Unknown", "❓")) do if an unlisted code is encountered?

Question 4

How does the application prevent hanging if the remote weather API is unresponsive?

Question 5

What method is called on the response object to confirm whether the HTTP status code was successful?

🚀 What's Next?

In the next lesson, we will continue your intermediate Python journey with Using print vs logging (9: Debugging and Logging).

👉 Continue to Next Lesson: Using print vs logging →

Next Lesson

Using print vs logging

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

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Using print vs logging

Project: Weather Data Fetcher in Python

Intermediate8 min read•Updated: 2026-10-01

Study Materials Cheatsheet

Project: Weather Data Fetcher

We will connect to the open, free Open-Meteo API (which requires zero API keys or credit cards) to look up city coordinates and fetch current meteorological telemetry.

1. System Architecture & API Endpoints

Our weather application performs a two-stage API pipeline:

1
Geocoding API: Resolves a user's textual city query (e.g. "Mumbai" or "London") into exact latitude and longitude coordinates.

Endpoint: https://geocoding-api.open-meteo.com/v1/search?name={city}&count=1

1
Forecast Weather API: Fetches current weather telemetry for those coordinates.

Endpoint: https://api.open-meteo.com/v1/forecast?latitude={lat}&longitude={lng}&current_weather=true

1
Data Translation Layer: Maps numerical WMO weather codes (e.g. Code 0 = "Clear Sky", Code 61 = "Slight Rain") to user-friendly status descriptions.

2. Complete Application Code

Visual Architecture & Process Flow

How data and code flow step-by-step

Flowchart

Step 1

def get_coordinates

self, city_name: str

Step 2

Optional[Tuple[float, float, str, str]]:

3. Sample Execution Simulation

1==================================================
2      REAL-TIME GLOBAL WEATHER DASHBOARD
3==================================================
4 
5Enter city name (or 'quit' to exit): New Delhi
6 
7Searching coordinates for 'New Delhi'...
8 
9==================================================
10       WEATHER REPORT: NEW DELHI, INDIA ☀️
11==================================================
12 Coordinates       : 28.61°N, 77.21°E
13 Condition         : Clear sky
14 Temperature       : 31.4°C (88.5°F)
15 Wind Speed        : 8.2 km/h
16 Wind Direction    : 295°
17==================================================
18 
19Enter city name (or 'quit' to exit): London
20 
21Searching coordinates for 'London'...
22 
23==================================================
24       WEATHER REPORT: LONDON, UNITED KINGDOM 🌧️
25==================================================
26 Coordinates       : 51.51°N, -0.13°E
27 Condition         : Slight rain
28 Temperature       : 14.2°C (57.6°F)
29 Wind Speed        : 19.8 km/h
30 Wind Direction    : 210°
31==================================================
32 
33Enter city name (or 'quit' to exit): quit
34Thank you for using the Weather Dashboard. Stay safe!

⚠️ Common Intermediate Mistakes & Gotchas

1. Unhandled Network Disconnection

Network drops raise requests.exceptions.ConnectionError. Always wrap API calls in a try-except block targeting requests.exceptions.RequestException.

2. Assuming City Names Are Always Valid

Handle 404 responses gracefully by informing the user that the city was not found rather than letting the application crash with a traceback.

💻 Try It Yourself: Extension Challenge - Temperature Unit Switch

Challenge

Extend the Weather Data Fetcher to accept a command-line flag (--unit C or --unit F) that converts temperatures between Celsius and Fahrenheit.

Complete Solution

1def convert_temp(celsius_temp: float, unit: str = "C") -> str:
2    if unit.upper() == "F":
3        fahrenheit = (celsius_temp * 9/5) + 32
4        return f"{fahrenheit:.1f}°F"
5    return f"{celsius_temp:.1f}°C"
6 
7# Test conversion
8print("28°C in Fahrenheit:", convert_temp(28.0, "F"))
9print("28°C in Celsius:", convert_temp(28.0, "C"))

Expected Output

128°C in Fahrenheit: 82.4°F
228°C in Celsius: 28.0°C

Interactive Quiz• Knowledge Check

Practice Quiz

Question 1

In this project, what is the role of the Geocoding API step?

Question 2

Why is self.session = requests.Session() instantiated inside the WeatherFetcher constructor?

Question 3

What does WEATHER_CODES.get(code, ("Unknown", "❓")) do if an unlisted code is encountered?

Question 4

How does the application prevent hanging if the remote weather API is unresponsive?

Question 5

What method is called on the response object to confirm whether the HTTP status code was successful?

🚀 What's Next?

In the next lesson, we will continue your intermediate Python journey with Using print vs logging (9: Debugging and Logging).

👉 Continue to Next Lesson: Using print vs logging →

Next Lesson

Using print vs logging

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Practical API Example	Using print vs logging

Practice Quiz

Test your understanding of this lesson with 5 questions. Each question has one correct answer.

Previous Next