Summer and high-latitude prayer times

Why a twilight angle can be unavailable

In most profiles, Fajr and Isha are linked to a twilight angle: the moment the sun is a set number of degrees below the horizon. The ISNA / North America profile, for example, uses 15°. On a winter night the sun usually sinks well past that angle, so both times occur.

In summer, the further a place is from the equator, the shallower the sun’s path below the horizon. The sun can set, travel just below the horizon and rise again without ever reaching the selected angle. On those nights the angle-based Fajr or Isha does not occur at all, even though sunset and sunrise still happen.

Whether this happens depends on latitude, date and the selected angle together. A 13° profile can still produce a time on a night when an 18° profile cannot. So there is no single latitude or date range at which every profile stops working. The diagram illustrates the idea and is not a measured plot for any particular city.

Persistent twilight and polar day are different

The difference matters because the ordinary night rules and the Moonsighting Committee’s seasonal bounds both depend on the calculation date’s sunset and the following sunrise. In persistent twilight those points exist, so a limit or seasonal estimate can be worked out. In polar day or night there may be no night to divide, and a fraction of a night that doesn’t exist cannot produce a time.

An interval Isha works differently. It counts from sunset, or from adjusted Maghrib if you choose that start point. On a night with a sunset, it can therefore give an Isha even when the sun never reaches the twilight angle. It cannot give an Isha without a sunset, and it does not fill in Fajr, sunrise or any other missing row. See entering a documented Isha interval for how these modes are set.

A row can also be unavailable when the sun stays so close to the horizon that the calculation cannot resolve a time. In all these cases the tool leaves the missing rows unavailable. It does not substitute a neighbouring city, a lower latitude or the nearest date with a full timetable.

Night-portion rules and the seasonal profile

Every profile except Moonsighting Committee uses one of four night rules, and you choose which. Each rule takes the night for a calculation date, from that date’s sunset to the following sunrise, and sets two limits. An angle-based Isha can be no later than sunset plus a share of that night. Fajr can be no earlier than the same date’s sunrise minus the same share:

• Angle-based: the share is the prayer’s twilight angle divided by 60. A 15° angle gives a quarter of the night, and an 18° angle gives three tenths.
• Middle of the night: half the night. The Isha limit falls at the midpoint of the night that follows that date’s sunset.
• One seventh of the night: one seventh.
• One-third of night (sunset to sunrise): one third of the same sunset-to-sunrise night.

The Fajr limit is a software bound. It reuses the length of the night that follows the calculation date and counts back from that date’s sunrise. It does not measure the night that actually comes before that Fajr.

These rules are limits, not automatic replacements. A limit is used only when the angle time doesn’t occur or would fall beyond the limit. If the angle gives a time inside the limit, that time stays and the row is not labelled as a limit. When a limit is used, the row says that a twilight rule limit was applied.

A fixed-interval Isha is the exception. It stays at its interval and is not limited by the night rule, while Fajr still follows the rule you chose. A custom Isha interval on selected dates behaves the same way while its date range is active. Keep this in mind when you compare an interval profile with an angle profile in summer.

The Moonsighting Committee profile

The Moonsighting Committee (seasonal twilight) profile handles summer nights with its own seasonal model, so the ordinary night-rule choice is hidden for it. It follows the Adhan 4.4.6 version of this model. The profile first works out Fajr and Isha from twilight angles and then applies its own seasonal bounds, which depend on the date and the latitude. At 55° north and above, it first uses a one-seventh-of-the-night value, as Adhan 4.4.6 does, and then applies the seasonal bounds. In the southern hemisphere the seasonal dates are shifted, but the 55° north step is not used.

The profile’s Twilight type setting defaults to General, and Ahmer (red) and Abyad (white) are available as options. This setting is separate from the Asr Standard or Hanafi choice. Each row says whether a seasonal twilight value or the 55° one-seventh value was used. If sunset or sunrise is missing, the rows that depend on it stay unavailable, as with every other profile.

Sources and limits of these options

The angle-based, middle-of-the-night and one-seventh rules, and the seasonal profile, follow the Adhan 4.4.6 high-latitude rule documentation for the library this tool uses. For the seasonal approach, see also the Moonsighting Committee’s own explanation of its method. The one-third rule uses the same limit method with a share of one third. It is a defined sunset-to-sunrise bound and is not presented as a copy of any mosque’s one-third approach (see documented local approaches below).

All of these are calculation options. They are not a claim that any rule has universal scholarly approval. The tool does not offer methods that take times from another latitude or city. For the profile angles these rules work with, see method parameters and Asr settings.

A dated Edmonton summer comparison

Two fixed examples at the same Edmonton point show how the ordinary night rules behave and how to read a late Isha. The tool’s own engine calculated both. They are dated examples, not current times.

21 June 2026: changing only the night rule

The comparison table uses this example:

• Place: Edmonton, 53.5461, −113.4938, America/Edmonton
• Date: 21 June 2026
• Profile: ISNA / North America (15° / 15°), Asr Standard
• Manual adjustments: none. Rounding: nearest minute

Only the night rule changes between rows. On this night the sun does not reach 15° below the horizon, so Fajr and Isha both come from the selected rule.

With one seventh of the night, Isha falls fairly soon after sunset on 21 June and Fajr fairly soon before sunrise. With middle of the night, Isha is placed half the night after the 21 June sunset. That moves it past local midnight, so it is shown with the date 22 June. Fajr is placed the same half-night length before the 21 June sunrise. The angle-based rule (a quarter of the night at 15°) and the one-third rule set their limits between these two.

The Moonsighting Committee profile does not use this night-rule choice, so it is not part of this comparison.

15 July 2026: a late Isha that is an angle time

This example uses these settings:

• Place: Edmonton, 53.5461, −113.4938, America/Edmonton (UTC−6 in July 2026)
• Date: 15 July 2026
• Profile: ISNA / North America (15° / 15°), Asr Standard
• Night rule: middle of the night
• Manual adjustments: none. Rounding: nearest minute

With these settings, Isha is 01:21 on 16 July 2026 (07:21 UTC). This is the calculated 15° crossing, rounded to the nearest minute. It is the time the sun’s centre passes 15° below the horizon as it sinks after the 15 July sunset.

Because the sun does cross 15° that night, the time comes from the angle, not from the night limit. It falls before the middle-of-the-night limit, so the rule does not change it and the row is not labelled as a limit. A late Isha after midnight is therefore not always an estimate. Check the row’s label as well as the hour.

Published mosque schedules for the same evening

Two Edmonton mosques publish their own timetables for this evening.

• Al Rashid Foundation’s monthly prayer calendar lists an adhaan time and a separate iqamah time for Isha. To see these times, choose July 2026 in the calendar’s month and year filter.
• Masjid Quba’s prayer times also list an Isha adhaan time and a separate iqamah time.
• The Masjid Quba yearly prayer timetable for 2026 has a single column headed Isha. We checked that column against Quba’s monthly adhaan times for every date from 1 June to 30 September 2026, and they match. That column therefore shows adhaan times.

These published schedules differ from our 15° example. Their Isha times fall on the evening of 15 July, about two hours before our 01:21 result.

We have not confirmed the full method behind either timetable. For that reason, the gap can’t be traced to a particular angle, interval, night rule or margin, and we don’t assume one. The gap doesn’t show that either mosque’s timetable is wrong.

The two schedules are close to each other, but that doesn’t tell us how either one was produced. No profile in this tool, including Moonsighting Committee, is an Al Rashid or Masjid Quba profile. Listing these schedules doesn’t mean either mosque uses or endorses this tool. When you compare, keep the adhaan and iqamah rows separate, because iqamah is a congregation time.

Look up the published times yourself

The published mosque calendars section below the calculator shows reviewed copies of these two schedules. To use it:

1. Choose Al Rashid or Masjid Quba Edmonton.
2. Choose a date and a time format.

The reviewed data covers 1 June to 30 September 2026 only, captured on 31 October 2026 (UTC). Other dates show no reviewed data. To go straight to this example, use Open 15 July 2026 example.

The daily view keeps adhaan times (with sunrise) separate from iqamah times. The monthly view and the CSV download show the source date of each row. Each view always shows its coverage, its capture time and a link to the mosque’s official timetable.

These are historical published times. They are not current times and not calculated values. The viewer does not carry them into another year, fill gaps or swap in calculated times. A date outside the reviewed range is shown as unavailable, and so is any cell held back during review. The official source link still works in both cases.

For example, Masjid Quba’s schedule gives a Maghrib iqamah of 00:00 on 6 July 2026. That time falls outside the window before the next prayer, so the viewer shows no time for that cell. Instead it asks you to check the official timetable, and it keeps the 22:05 Maghrib adhaan.

The viewer has no countdown. It needs no location permission and makes no requests to a prayer-times service.

Compare with your own settings

These calculated examples show how the settings behave on two dates. They are not an Edmonton mosque timetable, and they don’t account for terrain or the observed horizon.

To compare the rules for your location, choose any profile other than Moonsighting Committee. Keep every other setting the same and change only the night rule. If your result still differs from a published schedule, troubleshoot a time difference.

Point: 53.5461, −113.4938. ISNA 15° / 15°; Standard Asr; zero manual adjustments; nearest-minute rounding. These are calculated examples under the selected bounds.

Adhan 4.4.6 + twilight refinement 1 + seasonal strategies 1 · IANA timezone data 2026f

Read the event’s calendar date

Each timetable is calculated for a date, but a late Isha can land after midnight on the clock. The row still belongs to the timetable for its calculation date, while its clock time falls on the next calendar day. The tool shows this with a date badge on any time that crosses midnight.

Read the badge as well as the hour. If you looked only at the clock, an Isha shown at 00:40 might seem to come before Fajr, when it actually follows Maghrib. That time is only an illustration.

In the Today view, shortly after midnight the next prayer may be the previous timetable’s Isha, which is still to come, and the countdown shows it. With some middle-of-the-night settings, that Isha and the new timetable’s Fajr fall in the same displayed minute. The countdown then pauses rather than choosing one, and both rows stay visible with their dates. Sunrise is a solar marker and is never selected as the next prayer.

Use a documented local approach

Communities handle nights without twilight in different ways, and each approach is documented by the mosques and bodies that use it. Ask your mosque or local issuing body which approach its timetable follows.

For example, Edinburgh Central Mosque explains its abnormal summer times and its own one-third-of-the-night approach. That is a choice for that community, not a worldwide rule, and other bodies describe different approaches.

This tool’s One-third of night (sunset to sunrise) rule is a defined bound that measures the night from sunset to sunrise. We have not confirmed exactly when Edinburgh Central Mosque applies its approach or which start and end points it uses for the night. Don’t treat our one-third rule as a reproduction of that mosque’s timetable.

If you follow a particular mosque, use its current timetable as your reference for that mosque’s times. Check which column you are reading. A prayer start time or an adhaan time is not the same as an iqamah (congregation) time.

Don’t try to work out the mosque’s angle, interval, night rule or adjustment from one row, or from a few rows, because different settings can give the same time on one date. The dated Edmonton comparison above shows how far a published schedule and a calculated angle time can differ.

Instead, ask the mosque which approach it uses. If it gives you the values and the tool supports that approach, you can enter them in the tool and compare like with like.

Entering a documented Isha interval

If your mosque documents an Isha interval, the Custom profile may be able to hold it. Its Isha setting has four modes: Angle, Fixed interval, Interval on selected dates and Cap on selected dates.

• Interval length: intervals are whole minutes from 30 to 180.
• Where the interval starts: choose Unadjusted sunset, which is the default, or Maghrib with adjustments. With Maghrib with adjustments, changing your Maghrib minutes also moves Isha. With Unadjusted sunset, and in the other fixed-interval profiles, adjusting Maghrib does not move Isha. Your own Isha minutes are added last.
• Date range: the selected-date modes need a first and last full date between 2020 and 2035, inclusive. The range can cross the new year, but it does not repeat each year. It applies to the timetable date, even when Isha falls after midnight. Outside the range, Isha uses the selected angle and your night rule.
• Interval on selected dates: while the range is active, the interval sets Isha in the same way as a fixed interval.
• Cap on selected dates: while the range is active, a cap only moves Isha earlier, and only when the interval time is earlier. Otherwise the angle or limit time stays.

An interval can give an Isha time on a night when the sun never reaches the Isha angle. It counts from sunset, or from adjusted Maghrib if you choose that start point. It cannot create a sunset that doesn’t occur, so at a polar site with no sunset on the timetable date, Isha stays unavailable. A cap is different because it only moves an existing Isha earlier. It needs a calculated angle time or night-rule limit first, and that limit itself needs both sunset and the following sunrise. If neither exists, the cap has nothing to move and Isha stays unavailable. An interval Isha also doesn’t complete the rest of the timetable. Fajr still follows the chosen angle and night rule, and rows that depend on a missing sunrise stay unavailable. Each day’s details show the policy, twilight type, offsets, interval start, date range and whether the range is active that day.

Not every local convention can be entered here. If your mosque’s approach isn’t supported, use the mosque’s timetable rather than adjusting other settings to imitate it.

When the timetable is incomplete

When our tool can’t produce a complete timetable, it says so clearly:

• Missing rows are marked unavailable. They never show 00:00 or a substitute value.
• The live next-prayer countdown pauses instead of relying on an incomplete day.
• The printed month keeps the unavailable labels on each affected date and shows the criterion used for each Fajr and Isha row. It records your night rule or seasonal settings. Where a date range is set, it shows the full range rather than assuming the range covers the whole month.
• The published mosque calendars show reviewed dates only. Other dates and held cells are unavailable rather than filled with calculated times.

A calculator cannot answer questions about combining prayers, praying Isha early, fasting hours or hardship. Take those to knowledgeable local guidance. If your schedule still differs from another source, troubleshoot a schedule difference.