Build a Weather Forecast Desktop App with PyQt5 in Minutes

Development Environment

Python3

PyQt5

requests

Preparation Work

Download the city‑code CSV from HeWeather , read it with pandas, keep the City_ID and City_CN columns, extract the numeric part of City_ID, build a mapping dictionary, and save it as city_code.txt.

import pandas as pd
# Read the downloaded file named 'city_code.csv'
file = pd.read_csv('city_code.csv')
# Keep only the two needed columns
file = file.loc[:, ['City_ID', 'City_CN']]
# Show the first five rows
file.head()

# Extract numeric part of City_ID
import re

def convert(x):
    pat = re.compile('(\d+)')
    return pat.search(x).group()

file['City_ID_map'] = file['City_ID'].map(convert)

# Build city‑to‑code mapping dictionary

def city2id(file):
    code_dict = {}
    key = 'City_CN'
    value = 'City_ID_map'
    for k, v in zip(file[key], file[value]):
        code_dict[k] = v
    return code_dict

code_dict = city2id(file)

# Save the dictionary to a txt file
import json
filename = 'city_code.txt'
with open(filename, 'w') as f:
    json.dump(code_dict, f)

Later you can load the dictionary with:

with open(filename, 'r') as f:
    text = json.load(f)

UI Design

Design the interface with Qt Designer; the resulting layout looks like the image below.

Main Logic

The API endpoint used is http://wthrcdn.etouch.cn/weather_mini?citykey={code}. Replace {code} with the city code (e.g., 101191101 for Changzhou) and send a GET request. The service returns a JSON payload that can be parsed to extract weather details.

# Extract weather information
city = f"城市：{data['city']}
"
today = data['forecast'][0]
date = f"日期：{today['date']}
"
now = f"实时温度：{data['wendu']}度
"
temperature = f"温度：{today['high']} {today['low']}
"
wind = f"风向：{today['fengxiang']}
"
weather = f"天气：{today['type']}
"
tips = f"贴士：{data['ganmao']}
"

Fetch the JSON with requests.get and handle possible errors:

def query_weather(code):
    # Build request URL
    url = f'http://wthrcdn.etouch.cn/weather_mini?citykey={code}'
    try:
        resp = requests.get(url)
        resp.encoding = 'utf-8'
    except requests.ConnectionError:
        raise
    try:
        info_json = resp.json()
    except JSONDecodeError:
        return '无法查询'
    return info_json

Additional UI Controls

# Set textEdit to read‑only
self.textEdit.setReadOnly(True)
# Focus the lineEdit widget
self.lineEdit.setFocus()
# Get text from lineEdit
city = self.lineEdit.text()
# Set text in textEdit
self.textEdit.setText(info)
# Clear lineEdit
self.lineEdit.clear()

Define a shortcut for the query button by overriding keyPressEvent:

def keyPressEvent(self, e):
    # Trigger query on Enter key
    if e.key() == Qt.Key_Return:
        self.queryWeather()

Packaging

Package the application with PyInstaller:

pyinstaller -w weather.py

After building, copy city_code.txt into the dist/weather folder so the executable can locate the mapping file.

The complete source code and compiled executable can be obtained by replying with the keyword “天气”.