👀 Views: 78 💬 Answers: 1 📅 Created: 2025-08-21

python-3.x datetime pytz daylight-saving-time Python

I'm working on a project and hit a roadblock... I'm working on a personal project and I tried several approaches but none seem to work. I'm working with unexpected behavior when performing datetime arithmetic across different time zones using the `pytz` library in Python 3.8. Specifically, I'm trying to calculate the time difference between two datetime objects that are in different time zones, but I'm getting an incorrect result due to daylight saving time adjustments. Here's a simplified version of my code: ```python import pytz from datetime import datetime, timedelta # Define two time zones ny_tz = pytz.timezone('America/New_York') la_tz = pytz.timezone('America/Los_Angeles') # Create a datetime in New York ny_time = ny_tz.localize(datetime(2021, 11, 7, 1, 30)) # Daylight saving time ends # Create a corresponding time in Los Angeles on the same day la_time = la_tz.localize(datetime(2021, 11, 7, 1, 30)) # Calculate the difference time_difference = ny_time - la_time print(f'Time difference: {time_difference}') ``` When I run this code, I expect to see a time difference of 3 hours, but the output is showing `4:00:00`. The confusion seems to stem from the fact that New York has switched back to standard time while Los Angeles is still in daylight saving time. I've tried adjusting the datetime objects to ensure they are correctly localized, but the scenario continues. Is there a correct way to handle such cases where daylight saving time can affect the results? Any insights would be greatly appreciated! Is there a better approach? My development environment is Linux. Any help would be greatly appreciated! The project is a service built with Python. Could someone point me to the right documentation? I recently upgraded to Python LTS.