# US–UK time difference in March: the clock-change gap weeks

> New York is 4 hours behind London during US–UK clock-change gaps, instead of 5. See the March and October–November dates for 2026 and 2027.

URL: https://halqora.com/blog/us-uk-clock-change-gap-weeks
Last updated: 2026-10-21

Published: 2026-10-21 · By Halqora team

Different [US clock-change rules](https://nist.gov/pml/time-and-frequency-division/popular-links/daylight-saving-time-dst) and UK clock-change rules shrink New York’s gap with London from 5 hours to 4 during mismatch weeks. The windows are 8–29 March and 25 October–1 November 2026, and 14–28 March and 31 October–7 November 2027.

> **Key facts:** - As of 21 October 2026, US daylight saving time starts on March’s second Sunday and ends on November’s first, according to [NIST’s daylight saving rules](https://nist.gov/pml/time-and-frequency-division/popular-links/daylight-saving-time-dst).
> - UK clocks move forward on March’s last Sunday and back on October’s last Sunday, according to the UK government’s clock-change guide.
> - Toronto follows the US-style rule, with changes on 8 March and 1 November 2026, according to [IANA’s North American time-zone data](https://data.iana.org/time-zones/tzdb/northamerica).
> - Pakistan keeps a fixed clock: Karachi is 5 hours ahead of London during GMT and 4 hours ahead during BST, according to [IANA’s Asian time-zone data](https://data.iana.org/time-zones/tzdb/asia).

> **Definition:** A clock-change gap is the temporary period when places that normally change clocks have made different seasonal changes, altering their usual time difference.

## Why do the US and UK change clocks on different dates?

The US and UK use different calendar rules for daylight saving time. New York changes before London in spring and after London in autumn. Neither city’s clock is wrong during the gap. The cities are simply using different seasonal offsets, so a recurring lesson cannot keep the same local time in both cities throughout the year.

NIST gives the US change time as 2:00 am local time. The UK government gives the spring change as 1:00 am and the autumn change as 2:00 am. These rules, current as of 21 October 2026, produce the dates below.

Use city zones such as America/New_York and Europe/London when you schedule. Our guide to [scheduling across time zones](https://halqora.com/blog/schedule-online-classes-across-time-zones) explains how to choose a recurring class’s anchor.

## When are the gap weeks in 2026 and 2027?

The spring gap lasts 3 weeks in 2026 and 2 weeks in 2027; the autumn gap lasts 1 week in each year. These durations are calendar arithmetic from the official change dates. A lesson fixed at 5:00 pm London time moves from 12:00 pm to 1:00 pm in New York during each gap, then returns.

**Example: a class fixed at 5:00 pm London time.** Dates follow the official rules as of 21 October 2026; the 2027 windows are computed from those rules.

| Period | London clock | New York clock | Gap (hours) | New York time for a 5:00 pm London class |
| --- | --- | --- | --- | --- |
| 2026 winter, before 8 March | GMT | EST | 5 | 12:00 pm |
| 8–29 March 2026, US on DST before UK | GMT | EDT | 4 | 1:00 pm |
| 29 March–25 October 2026, summer | BST | EDT | 5 | 12:00 pm |
| 25 October–1 November 2026, UK back before US | GMT | EDT | 4 | 1:00 pm |
| 2027 winter, before 14 March | GMT | EST | 5 | 12:00 pm |
| 14–28 March 2027, US on DST before UK | GMT | EDT | 4 | 1:00 pm |
| 28 March–31 October 2027, summer | BST | EDT | 5 | 12:00 pm |
| 31 October–7 November 2027, UK back before US | GMT | EDT | 4 | 1:00 pm |

The boundary dates are clock-change Sundays, not whole days with a single gap. The gap starts after the earlier city changes and ends when the later city changes. For the afternoon lesson shown, the end-date Sunday already uses the next row’s time. After the November change, winter times return.

Keep the [DST calendar for 2026–2027](https://halqora.com/blog/daylight-saving-time-online-classes-2026-2027) alongside your class schedule when checking transition dates.

## Who notices the shift when their clock has not moved?

The participant whose clock has not moved may see a different lesson time, depending on the class’s anchor. A London-anchored class keeps its London time, so the New York participant sees the change. A New York-anchored class keeps its New York time, so the London participant sees the change. The anchor determines whose daily routine stays steady.

**Example:** a class fixed at 12:00 pm New York time is normally at 5:00 pm London time. During the gap, adding the 4-hour difference gives 4:00 pm London time.

Avoid telling everyone to “move the lesson forward.” That instruction leaves the clock and direction unclear. Give each participant a date, a local start time, and a city.

## How do the changes affect Pakistan, the Gulf, and Canada?

Pakistan and the Gulf do not follow London or New York through seasonal clock changes. A teacher there can see UK classes shift on the UK date and US classes shift on the US date. Canada needs a city check: Toronto follows the US dates, while British Columbia’s rule changed in 2026. A country label is not enough.

**Example: a lesson fixed at 5:00 pm Karachi time**, using the offsets in IANA’s Asian and North American data as of 21 October 2026.

| Period in 2026 and 2027 | Karachi lesson time | London lesson time | New York lesson time |
| --- | --- | --- | --- |
| Winter, before the US change | 5:00 pm | 12:00 pm | 7:00 am |
| March gap, before the UK change | 5:00 pm | 12:00 pm | 8:00 am |
| Summer, after the UK change | 5:00 pm | 1:00 pm | 8:00 am |
| Autumn gap, before the US change | 5:00 pm | 12:00 pm | 8:00 am |

Saudi Arabia stays at UTC+3 and the UAE at UTC+4, according to the same Asian data. Riyadh is 8 hours ahead of New York in winter and 7 hours ahead during US daylight saving time.

As of 21 October 2026, [British Columbia’s government says its March change was its final clock change](https://www2.gov.bc.ca/gov/content/governments/celebrating-british-columbia/daylight-saving-time). B.C. stays at UTC−7 and will not fall back on 1 November 2026. Do not reuse Toronto’s instructions for a B.C. family.

## Which side’s lesson time should change?

Choose the class’s anchor according to the routine you have agreed to protect. A family’s after-school slot may need to stay fixed, or a teacher’s availability may set the limit. Neither choice removes the time difference. Agree on the anchor, check the other participant’s availability, and record the decision before changing any recurring lesson.

1. Confirm the class’s named time zone and agreed local start time.
2. Check both participants’ local times during the gap and after the next change.
3. Resolve conflicts with the teacher and family before publishing the schedule.
4. Record any temporary exception separately from the recurring agreement.

Check nearby lessons too: a shifted class can clash with another family’s lesson.

## What should you tell families before the gap weeks?

A family message should state what stays fixed, the temporary local times, and the date normal times return. Name both cities rather than relying on seasonal abbreviations. Ask the family to confirm the stated time if availability is uncertain. Send the same confirmed details to the teacher so both participants work from the same agreement.

**Example message for a London-anchored class:**

> Your lesson stays at 5:00 pm London time. From 25 October 2026 until the US clock change on 1 November, that is 1:00 pm in New York. From 1 November, your lesson is back at 12:00 pm New York time. Please confirm that the temporary New York time works for you.

Replace the dates and times with the confirmed schedule before sending. State any temporary exception directly.

## How Halqora handles this

Halqora is management software for online academies: [Halqora scheduling](https://halqora.com/features/scheduling) stores scheduling rules in each IANA time zone to keep the agreed local time, while the academy decides whose time zone anchors the class.

## Sources

- [NIST’s daylight saving time rules](https://nist.gov/pml/time-and-frequency-division/popular-links/daylight-saving-time-dst), checked 21 October 2026
- UK government clock-change dates, checked 21 October 2026
- [IANA North American time-zone data](https://data.iana.org/time-zones/tzdb/northamerica), checked 21 October 2026
- [IANA Asian time-zone data](https://data.iana.org/time-zones/tzdb/asia), checked 21 October 2026
- [British Columbia’s daylight saving time announcement](https://www2.gov.bc.ca/gov/content/governments/celebrating-british-columbia/daylight-saving-time), checked 21 October 2026

## Questions

### Why is the US–UK time difference only 4 hours in March?

The US starts daylight saving time on March’s second Sunday, while the UK changes on March’s last Sunday. New York moves forward before London, reducing their usual 5-hour difference to 4 hours. The gap lasts 3 weeks in March 2026 and 2 weeks in March 2027. A similar gap returns between the UK’s October change and the US’s November change.

### Which side’s lesson time should change during the gap weeks?

Choose which time zone owns the recurring class. If a class stays at 5:00 pm London time, the New York participant attends at 1:00 pm during the gap instead of 12:00 pm. Agree on the anchor before the clocks change, check the teacher’s availability, and tell both sides the dated local times and when the temporary difference ends.

### Does this affect Canada?

Toronto follows the US clock-change dates, so Toronto has the same mismatch windows with London as New York in 2026 and 2027. British Columbia is different: according to the provincial government’s position as of 21 October 2026, its March 2026 change was its final change, and it stays at UTC−7. Check the Canadian city rather than assuming a countrywide rule.

### Does it affect classes with teachers in Pakistan?

Yes. Pakistan keeps the same clock throughout the year, while UK and US clocks change on different dates. A lesson fixed at 5:00 pm Karachi time is at 12:00 pm in London during GMT and 1:00 pm during BST. In New York, the same lesson is at 7:00 am during EST and 8:00 am during EDT.