Why is solar noon different from clock noon?
Quick Answer: Solar noon happens when the sun is highest in the sky at your location. Clock noon, or 12:00 PM, is set by time zones and standard time, so they often don’t line up perfectly.
Solar noon depends on your exact longitude and the Earth's orbit, so it shifts slightly every day. Clock noon is fixed by political boundaries and time zones, which cover wide areas.
Also, daylight saving time can shift clock noon away from solar noon by an hour. That’s why the sun may peak before or after your clock says 12 PM.