Why does the time difference with the United States change during certain weeks of the year?

Because Europe and the United States do not switch to daylight saving time or standard time on the same dates. For two to three weeks in March and about a week between October and November, their clock-change schedules do not align, causing the time difference to shift by one hour.

How can I avoid confusion when inviting someone abroad to a meeting?

Send a formal calendar invite rather than agreeing on a time in the body of a message. Calendar apps automatically convert the event to the recipient's local time zone.

What is the difference between CET and CEST?

CET (Central European Time) is standard or winter time across much of Europe (UTC+1), whereas CEST (Central European Summer Time) is daylight saving time (UTC+2). Confusing the two in an email can cause an hour's discrepancy.

Published on 5 October 20264 min readMadrugo team

Cross-time-zone meetings: rules to avoid being an hour early or late

Managing cross-border meetings flawlessly means understanding daylight saving transitions and always relying on calendar invites with fixed time zones.

Email Calendar and tasks Apple and wearables

The short answer: never arrange an international meeting simply by saying "at four". Always send a formal calendar invite (which converts the time automatically to each attendee's local zone) or specify the reference zone alongside its code and UTC offset. Pay close attention to the clock-change weeks in spring and autumn, as daylight saving transitions do not happen simultaneously across the world.

Coordinating a call between Madrid, London, and San Francisco sounds straightforward enough—until someone joins the video link sixty minutes early or late. Almost every mistake when scheduling international calls stems from three oversights: doing mental maths in the body of an email, failing to specify whether you mean standard or daylight saving time, and forgetting that seasonal clock changes happen on different dates depending on the region.

The danger of working out times in the body of an email

The most common pitfall is agreeing a time in writing with phrases like "I'll ring you at 10:00 my time" or "at 15:00 CET". A simple mental slip when adding up hours or confusing Central European Time (CET) with Central European Summer Time (CEST) is all it takes for the meeting to fall through.

To prevent this in your calendar and task management, stick to two basic rules:

Always use calendar invites: Google Calendar, Microsoft 365, and Apple Calendar all store events in Coordinated Universal Time (UTC). When you invite someone to a meeting, their software automatically converts the exact time to their local settings without anyone having to do any calculations.
If you write the time in a message, include the city and UTC: If you must write the time out in plain text, specify a reference city and the offset: for instance, "17:00 Spanish mainland time (UTC+2)".

The trap of seasonal clock changes

In the European Union and the UK, the autumn clock change happens on the last Sunday in October. In the United States, however, it takes place on the first Sunday in November. A similar gap occurs in spring: North America puts its clocks forward two or three weeks earlier than Europe.

During that transitional window, the usual time difference between cities shifts. If you are normally nine hours ahead of Los Angeles, the gap might only be eight hours for a couple of weeks. Anyone relying on memorised rules of thumb ("they're six hours behind") will get caught out during these periods. Your digital calendar, on the other hand, factors in these shifts automatically—provided appointments are created as calendar events rather than simple text notes.

Enable a secondary time zone on your main calendar

If you work daily with clients or colleagues in a specific country, keep their time zone visible:

In desktop or web views: Most calendar applications allow you to display a secondary time-zone column. Having it visible helps you see what time it is for the other person before suggesting a slot, saving you from proposing calls during their lunch break or outside their working hours.
Check your system settings: Ensure your computer and mobile phone have network-provided automatic time zones enabled. Alternatively, if you travel frequently and do not want fixed appointments shifting around, lock your calendar to your primary working time zone.

How to protect the boundaries of your working day

Working with people to the west (such as the Americas) pushes calls towards your late afternoon or evening, while collaborating with Asia brings meetings forward into early morning. Without clear boundaries, your working day can quickly spiral out of control.

A great practice is to set up time blocks on your calendar to clearly mark the start and end of your availability for external calls. In Madrugo, by bringing together your Google, Microsoft, iCloud, or iCal calendars alongside your tasks and email on a single screen, it is easy to get a complete picture of your day at a glance and spot early on whether an international meeting has been booked at an inconvenient time.

Frequently asked questions

Why does the time difference with the United States change during certain weeks of the year?: Because Europe and the United States do not switch to daylight saving time or standard time on the same dates. For two to three weeks in March and about a week between October and November, their clock-change schedules do not align, causing the time difference to shift by one hour.
How can I avoid confusion when inviting someone abroad to a meeting?: Send a formal calendar invite rather than agreeing on a time in the body of a message. Calendar apps automatically convert the event to the recipient's local time zone.
What is the difference between CET and CEST?: CET (Central European Time) is standard or winter time across much of Europe (UTC+1), whereas CEST (Central European Summer Time) is daylight saving time (UTC+2). Confusing the two in an email can cause an hour's discrepancy.