Clock changes are easy to ignore until an automation fires an hour late or a report shows two 1am buckets. In 2026, UK and EU clocks go back on Sunday 25 October and US and Canadian clocks go back on Sunday 1 November. If you email international audiences, there is a one-week window where the gap between regions is different from normal.
What you will learn:
- Which dates matter and why the gap between regions changes
- How to check scheduled sends, automations and integrations
- How to avoid reporting mistakes
- A short checklist and a worked example
The Short Version
- UK and EU clocks change on 25 October 2026; US and Canada on 1 November 2026.
- Between those dates, the UK-to-US east-coast time gap is 4 hours instead of the usual 5.
- Review all scheduled sends, automations and integrations for time-zone settings.
- Report in a consistent time basis and flag the extra hour.
- Compare local-time engagement, not raw UTC hours, across the change.
Direct answer: audit schedules that depend on fixed UTC or fixed offsets, confirm that your ESP uses time-zone-aware scheduling, and mark the weeks of the change in your analytics so you do not misread normal variation as a trend.
Dates and the Temporary Gap
| Date (2026) |
What happens |
Why it matters |
| Sun 25 October |
UK and EU clocks go back one hour |
UK sends at fixed UTC now arrive an hour earlier local time |
| 25 October to 1 November |
UK is on GMT; the US east coast is still on daylight time |
Gap between London and New York is 4 hours |
| Sun 1 November |
US and Canada clocks go back |
Normal 5-hour London to New York gap returns |
If you rely on a single send for a global audience, the arrival time in London and New York will differ by one hour from the usual pattern during the week.
Where Things Can Go Wrong
- Fixed-UTC schedules. A campaign scheduled for 14:00 UTC arrives at 15:00 in London during summer time and 14:00 after clocks go back.
- Recurring automations. A weekly send set by a local time rule may skip or duplicate across the change if the platform handles it poorly.
- Integrations. Scripts, webhooks and spreadsheets that use local time can misalign.
- Reports. Hourly charts may show a repeated hour on fallback day.
- Time-zone segments. If you segment by user time zone, ensure daylight saving is applied correctly.
A Checklist for This Week
The timezone send optimizer and send time optimizer can help you plan.
Worked example: local arrival time
You schedule a campaign for 13:00 UTC on Wednesday 28 October.
- London (GMT, UTC+0 after 25 October): 13:00 local.
- New York (EDT, UTC−4 until 1 November): 09:00 local.
- Gap: 13:00 − 09:00 = 4 hours.
The same 13:00 UTC send on Wednesday 4 November arrives at 08:00 in New York (EST, UTC−5), so the gap returns to 5 hours (13:00 − 08:00). If your best New York window is 09:00, the second send is an hour early for that audience. If you need a consistent local arrival time, use recipient-time-zone scheduling or adjust the UTC time.
Reporting Without Confusion
- Choose one time basis (UTC or recipient local time) and stick to it.
- Label the fallback hour. On the day clocks go back, one local hour occurs twice.
- Compare like with like. Compare Tuesday 9am local with another Tuesday 9am local, not a raw hour index.
- Avoid week-over-week conclusions across the change without annotation.
- Watch unsubscribes and complaints, which can shift with timing but should not be explained away without evidence.
Read about reporting pitfalls in why email metrics don't match your ESP dashboard and email send time optimisation.
Should You Change Your Send Time?
The darker evenings may change when people read email, but the effect varies by audience. Avoid permanent changes based on one week. Instead:
- Keep a control send time for a few weeks.
- Test an alternative on a randomised portion of the list.
- Evaluate on clicks and conversions, not open rate.
For a testing plan, use the A/B test calculator.
Common Mistakes
- Assuming your ESP handles everything.
- Forgetting integrations that run outside the ESP.
- Comparing hourly graphs without noting the repeated hour.
- Declaring a new best send time after one week.
- Ignoring countries that do not change clocks.
A one-hour shift is small, but it breaks anything that quietly assumed time stands still.
Key Takeaways
- UK and EU clocks change on 25 October; US and Canada on 1 November.
- The London to New York gap is 4 hours for a week.
- Audit schedules, automations and integrations.
- Report on a consistent time basis and annotate.
- Test before changing send times permanently.
Sources and Further Reading
Related Articles
Related tools: timezone send optimizer, send time optimizer, A/B test calculator, frequency planner.
Disclaimer: This article is general guidance. Check official time-zone rules for your regions. Example times and figures are illustrative.
