What is daylight saving time and how it affects video calls
Understand DST transitions, who still observes them, and how to avoid surprise one-hour shifts on calls.
Last updated: 2026-08-31
Why clocks shift
Daylight saving time (DST) moves civil clocks forward in spring and back in autumn so evenings have more daylight. The practice is political, not astronomical: regions choose whether to participate and on which Sundays to switch. That is why a video call that worked at 15:00 last month might need to be 16:00 today without anyone traveling.
Impact on remote work
When only one side of a call changes clocks, the gap between zones grows or shrinks by one hour. Example: New York and London are five hours apart in winter but four hours apart during overlapping summer weeks. Tools that store 'every Tuesday at 3 pm local' without zone metadata will fire at the wrong instant once a year.
Always schedule with an explicit IANA zone (Europe/Madrid, America/New_York) and verify on the actual meeting date using a DST-aware converter.
Regions that skip DST
Japan, South Korea, China, India, most of Arizona, Hawaii, and many Latin American countries stay on a fixed offset year-round. Saskatchewan in Canada and Queensland in Australia also skip seasonal shifts. Never assume your partner changes clocks just because your country does.
Frequently asked questions
- Do EU and US switch on the same day?
- Usually not. The US moves on March/November Sundays; the EU uses the last Sundays of March and October. For a few weeks each year the offset between them differs from the usual table.