Twice a year a reliable wave of messages arrives: my prayer app is an hour out since the clocks changed. Almost always the app is correct and something about the phone, the notification or the expectation is not — but the confusion is reasonable, because the printed times really do jump by an hour overnight while nothing in the sky has moved at all.
We computed the London times either side of both 2026 changes to show exactly what happens.
What the numbers do
Muslim World League angles, London coordinates, local clock time. The UK moves forward on 29 March 2026 and back on 25 October 2026.
Read down the columns and the pattern is clear. On ordinary days each time drifts by one to three minutes as the earth moves along its orbit. On the changeover day everything jumps by almost exactly an hour in one step — forward in March, backward in October — and then resumes its two-minute drift.
The sun did not move. The clock did. Fajr on 28 March and Fajr on 29 March are separated by about fifty-eight minutes of clock time and about two minutes of actual daylight.
| Day | Fajr | Sunrise | Maghrib | Isha |
|---|---|---|---|---|
| Fri 27 Mar | 03:51 | 05:47 | 18:25 | 20:15 |
| Sat 28 Mar | 03:49 | 05:45 | 18:27 | 20:17 |
| Sun 29 Mar | 04:46 | 06:43 | 19:29 | 21:19 |
| Mon 30 Mar | 04:43 | 06:41 | 19:30 | 21:21 |
| Day | Fajr | Sunrise | Maghrib | Isha |
|---|---|---|---|---|
| Fri 23 Oct | 05:46 | 07:38 | 17:51 | 19:36 |
| Sat 24 Oct | 05:48 | 07:40 | 17:49 | 19:34 |
| Sun 25 Oct | 04:49 | 06:42 | 16:47 | 18:32 |
| Mon 26 Oct | 04:51 | 06:43 | 16:45 | 18:30 |
Why autumn causes more trouble than spring
The spring change pushes everything later, which is psychologically easy — Maghrib moves from 18:27 to 19:29 and the evening feels longer. Nobody misses a prayer because its window opened later than expected.
The autumn change does the opposite, and it is brutal on the evening prayers. Maghrib falls from 17:49 on Saturday to 16:47 on Sunday. Someone used to leaving the office and praying Maghrib at half past five arrives home on Sunday to find the window opened three quarters of an hour ago and Isha is at 18:32. The whole evening has been pulled forward into what still feels like the afternoon.
This is also the weekend when Asr gets genuinely tight in northern latitudes, because sunset is now before five and the Asr window is squeezed from both ends. We measured those windows across the year in when does each prayer's time end; London's Dhuhr window in deep winter is only about an hour and a half.
When the app really is wrong
The times themselves are computed from solar geometry and then rendered in whatever time zone the device reports, so they cannot be off by an hour unless the device's idea of its own zone is wrong. That does happen, and there are a few specific causes worth checking before concluding the app is broken.
- The time zone is set manually. If automatic time zone is switched off — often done while travelling and never switched back — the phone keeps the old offset through the changeover and every prayer time inherits the error. This is by a wide margin the most common cause.
- The app has a manual location, not a manual zone. Some apps let you pin a city for prayer times while the device clock follows your actual location. If you pinned a city in a country that changes its clocks on a different date — the EU, the UK and the US do not change on the same weekend, and much of the world does not change at all — you get a genuine mismatch for a fortnight, and it resolves itself.
- Notifications were scheduled before the change. This one produces a real failure rather than a display error. Alerts scheduled days in advance against a wall-clock time can fire an hour out, or not fire, depending on how they were registered. A well-built app reschedules when the device reports a time-zone change; if yours does not, opening the app once after the change is enough to fix it. The general shape of notification failures is in why prayer notifications don't arrive.
- Your country abolished the change and the app didn't notice. Turkey has been on permanent UTC+3 since 2016 and no longer changes at all; Russia stopped in 2014. Devices get this right through their time-zone database, but a hardcoded offset somewhere in an app's settings will not.
The one thing worth doing
On the Saturday before a change, check that automatic time zone is on, and open your prayer app once on the Sunday morning so anything it schedules is rebuilt against the new offset. That is the whole of the maintenance.
And if the times still look wrong after that, the disagreement is probably not about the clock at all but about calculation angles, which move Fajr and Isha far more than an hour in some places. We measured five methods across eight latitudes for a full year in why prayer time apps disagree.
Common questions
- Do prayer times change with daylight saving?
- The printed times jump by an hour because the clock moved, not because anything solar changed. In London, Fajr goes from 03:49 on 28 March 2026 to 04:46 on 29 March — about fifty-eight minutes of clock time and roughly two minutes of actual daylight difference.
- Why is my prayer app an hour out after the clocks changed?
- Almost always the device's time zone is set manually rather than automatically, so it kept the old offset. Less often, the app is pinned to a city whose country changes its clocks on a different date, which corrects itself within a couple of weeks.
- Which clock change is harder to adjust to?
- The autumn one. In London, Maghrib drops from 17:49 to 16:47 overnight and Isha to 18:32, so the evening prayers arrive while it still feels like afternoon. The spring change pushes everything later, which nobody misses a prayer over.
- Do prayer notifications survive the clock change?
- They should, if the app reschedules when the device reports a time-zone change. Alerts registered against a wall-clock time days in advance can fire an hour out. Opening the app once after the change forces a rebuild.