DST: Why It Breaks Meetings

The DST problem stated plainly

Daylight saving time is politics masquerading as scheduling. Each country picks its own switch dates, some abandon the idea for a decade, others reboot it overnight. When one region jumps and another doesn’t, the overlap you relied on disappears. Calendars dutifully adjust local labels but rarely shout, “Hey, your teammate now sees this at 06:00.” Cue missed stand-ups, angry exec briefings, and on-call handoffs that fire while someone is still asleep.

Treat DST like a production change: know the maintenance window, rehearse the weird weeks, and keep a tool handy so you can paste the new offsets instead of arguing about who misread Outlook.

How drift actually happens

The IANA tz database publishes the exact Sunday (or Thursday) each region flips. When those Sundays differ, UTC offsets diverge for a week or three. Nobody edits the invite, yet a 09:00 New York / 17:00 Berlin split quietly becomes 09:00 / 16:00. Drop the cities into the Timezone planner and scrub through March—you will literally see the overlap bar shrink.

Try a US-East, Berlin, Sydney trio: New York moves the second Sunday in March, Berlin the last, Sydney the first Sunday in April. That’s three consecutive waves where somebody’s 09:00 turns into 05:00. Unless you plan for it, the call stays put and resentment builds.

Examples from real teams

Example: Weekly incident review

Wednesday incident review sits at 15:00 London / 10:00 New York. March arrives, London stays on UTC+0 for three more weeks while New York jumps to UTC-4. Suddenly the invite reads 11:00 for the US lead. No warning, so the facilitator assumes a no-show. One line in the DST Planner (“Weeks of 11–25 Mar: US +1h”) would have spared the accusatory Slack thread.

Example: APAC onboarding

Singapore enablement partners with Melbourne. Singapore never shifts; Melbourne toggles between UTC+10 and UTC+11. During Australian summer, the usual two-hour gap becomes three. Keep the session at 09:00 Singapore and you quietly push Melbourne from 11:00 to noon—right over their lunch block. A simple Timezone check lets you either reset the slot or rotate presenters for that quarter.

The mental model

Picture DST as a wave marching around the globe. Each city gets hit on a different weekend. When the wave passes, the overlap moves unless you paddle back. The Timezone grid lets you watch the wave in motion; the DST Planner gives you exact dates so you can warn people ahead of time.

Ready to operationalize it? Jump into the recurring meetings playbook and wire these dates into your invites, rotations, and comms.

FAQ

Why don’t calendars warn me before DST?

Most clients assume you read the news. A tiny banner is all you get. Paste a DST Planner link into the invite if you want the warning to live where people actually look.

Can I disable DST entirely?

Only by forcing everyone onto UTC or hiring exclusively from regions without DST. Otherwise you adapt every recurring meeting when local law shifts the offset.

What about Southern Hemisphere teams?

Their DST runs opposite the north, so October and April become danger months where only one side of the call flips. Plan for those just like March.

Do the rules change often?

Constantly. Governments announce changes with weeks of notice. Always check the upcoming year in the DST Planner or grab the latest tzdata release before declaring victory.