Building a Weather App with Python + Streamlit: wttr.in API Tutorial

Building a Weather App with Python + Streamlit (Using wttr.in API)

Sabin Sim built a weather app using Python and Streamlit, leveraging the wttr.in API for live weather data without API keys. The project includes both console and web versions with JSON parsing and error handling.

Why This Matters

The ideal model assumes seamless API access, but real-world systems face challenges like inconsistent data formats and network errors. For example, wttr.in returns JSON but requires strict parsing—missing a key like current_condition would crash the app. Error handling (e.g., checking response.status_code) is critical to avoid silent failures in production.

Key Insights

• “wttr.in requires no API key, 2025”: Ideal for quick prototyping but lacks advanced features like forecasts.
• “Streamlit for rapid web apps”: Used by developers to turn Python scripts into interactive dashboards with minimal code.
• “JSON parsing edge cases”: The current_condition array must be indexed properly ([0]) to avoid IndexError.

Working Example

# Console Version (weather.py)
import requests
city = input("Enter city name: ")
url = f"https://wttr.in/{city}?format=j1"
response = requests.get(url)
if response.status_code != 200:
    print("Error fetching weather data.")
    exit()
data = response.json()
current = data["current_condition"][0]
print("=== Weather Report ===")
print("City:", city)
print("Temperature:", current["temp_C"], "°C")
print("Weather:", current["weatherDesc"][0]["value"])
print("Humidity:", current["humidity"], "%")

# Streamlit Version (weather_streamlit.py)
import streamlit as st
import requests
st.title("🌤️ Sabin's Weather App")
city = st.text_input("Enter city name:", "Chur")
if st.button("Check Weather"):
    url = f"https://wttr.in/{city}?format=j1"
    response = requests.get(url)
    if response.status_code != 200:
        st.error("Error fetching weather data.")
    else:
        data = response.json()
        current = data["current_condition"][0]
        temp = current["temp_C"]
        desc = current["weatherDesc"][0]["value"]
        humidity = current["humidity"]
        st.subheader(f"Weather in {city}")
        st.write(f"🌡 Temperature: <strong>{temp}°C</strong>", unsafe_allow_html=True)
        st.write(f"☁ Condition: <strong>{desc}</strong>", unsafe_allow_html=True)
        st.write(f"💧 Humidity: <strong>{humidity}%</strong>", unsafe_allow_html=True)

Practical Applications

• Use Case: A lightweight dashboard for personal weather tracking using Streamlit.
• Pitfall: Forgetting to handle response.status_code may lead to uncaught exceptions in production.

References:

• https://dev.to/ian_b838138a27a917398d181/my-project-3-building-a-weather-app-with-python-streamlit-5423

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