All festivals and fasting days listed on Drik Panchang are location based i.e. geo location is considered while calculating date of Hindu events.
One interesting fact of location based Hindu events is that the event might be observed one day ahead in US cities and one day later in Australian cities compare to observance date for Indian cities. This goes opposite to time zone rule, and it creates too much confusion for those who calculate Hindu events based on time zone shift. As per time zone shift, if Diwali Lakshmi Puja date for New Delhi, India falls on Nov 04, 2021, then date for
Seattle, USA should fall on Nov 05, 2021 as Seattle clock is behind by 12.5 hours that of New Delhi. In fact, as per Deepavali observance rules, actual date for Seattle, USA is Nov 03, 2021, i.e., one day before New Delhi.
Please try to understand the phenomena with diagram given above. Amavasya Tithi prevails across the globe at the same time and whenever it happens day in US cities is one day ahead of India. As Amavasya Tithi might split between two days on Gregorian calendar, the preferred day is when it overlaps with Sunset. For illustration date, Tithi begins in New Delhi as well as in Seattle at the same moment, in New Delhi it was just before Sunrise and in Seattle it was just before Sunset, but the critical moment was one day ahead in Seattle. It should also be noted that observance date would either coincide or ahead of New Delhi based on "critical time" but never after New Delhi date.
Hope it clears why in US cities or even European cities festival is observed one day ahead of Indian observance day and for Japan, Australia, New Zealand, etc. the festival is observed one day after India.