Yom Kippur 2026 begins at sunset on Sunday, September 20, 2026, and ends at nightfall on Monday, September 21, 2026. The fast day itself falls on the Hebrew date of 10 Tishrei 5787. Jewish holidays begin at sunset, so the observance spans two Gregorian calendar dates even though it is a single Hebrew day. The precise start and end times depend on your location's sunset and nightfall calculations.
How the Hebrew calendar places Yom Kippur
The date is fixed in the Hebrew calendar but floats on the Gregorian one, and understanding why requires looking at how the lunisolar system works. The Hebrew calendar is lunar, with each month beginning at the new moon. Twelve lunar months total roughly 354 days, about 11 days short of a solar year. Left uncorrected, holidays would drift backward through the seasons by about 11 days annually, and Yom Kippur would eventually land in summer or spring.
The fix is the leap month of Adar I, inserted seven times in every 19-year cycle. This Metonic cycle keeps the lunar calendar aligned with the solar year within a small margin. The 19-year pattern contains 235 lunar months, which equals almost exactly 19 solar years. That is why Yom Kippur always falls in autumn, between early September and early October on the Gregorian calendar.
Yom Kippur is set on 10 Tishrei, the tenth day of the seventh month in the Hebrew religious year (Tishrei is the first month of the civil year). The timing is deliberate and textually anchored. The Torah designates it as a day of atonement, and the number ten carries weight throughout the season. The ten days from Rosh Hashanah (1 Tishrei) to Yom Kippur are treated as a period of reflection and repair.
The 2026 observance falls early in the September-to-October window. In Hebrew year 5787, Rosh Hashanah lands on September 12, 2026. That places Yom Kippur eight days later and produces the September 20 evening start. The calendar is not arbitrary; the position of 5787 within the 19-year cycle largely fixes the Gregorian placement.
Why start and end times vary by city
Jewish days run from sunset to nightfall rather than midnight to midnight, so "when is Yom Kippur" has a location-specific answer. Sundown marks the transition. The fast concludes the following night when three stars are visible, approximated by a calculated time called tzeit hakochavim.
The latitude of your city changes both numbers substantially. At higher latitudes, sunset shifts more dramatically across the year, and nightfall (the end of twilight) stretches longer in summer and shorter in winter. A city like Jerusalem and a city like Oslo will not see identical clock times, even though the day itself is identical.
The fast's duration therefore varies. In the contiguous United States at mid-latitudes, the 25-hour fast commonly runs roughly from about 7 p.m. to 8 p.m. the next day in late September, but the exact clock values differ by time zone and date. Communities publish their own zmanim (halachic times), which may use different twilight definitions.
| Location type | Sunset Sept 20 (approx.) | Fast ends Sept 21 (approx.) | Fast length |
|---|---|---|---|
| Mid-latitude US city | Early-to-mid evening | About 25 hours later | Near 25 hours |
| High-latitude city | Later clock time in summer | Long twilight window | Near 25 hours |
| Equatorial city | Close to a 6 p.m. sundown | Roughly 12 hours of darkness | Near 25 hours |
| Israel (Jerusalem) | Standard local sundown | Nightfall per local custom | Near 25 hours |
Treat these as approximate. Local halachic authorities set final times, and the table illustrates variation rather than supplying your community's schedule.
The 25-hour fast: physiology and the clock
A Yom Kippur fast involves no food and no water for roughly 25 hours. The extra hour beyond 24 arises because the day begins before sundown and ends after nightfall. The mechanism behind the timekeeping is astronomical, not arbitrary.
When you stop eating, the body first draws on glycogen stored in the liver, which can supply glucose for several hours. As glycogen depletes, the body shifts toward fat oxidation and, to a lesser degree, gluconeogenesis, the creation of glucose from other sources. This is why mild fatigue, headache, and irritability are common in the later hours. The shift is normal physiology, not a sign of harm in healthy adults.
Dehydration develops alongside the food fast because no fluid is taken. Even modest fluid loss can produce thirst, dark urine, and a dull headache. For most healthy people these are uncomfortable but self-limited and reverse quickly after the fast ends. The professional caveat: hydration status and medication timing interact, and individuals with chronic conditions should consult their own clinician and rabbi well before the date.
The 2026 timing matters for heat. A late-September fast in the Northern Hemisphere avoids peak summer temperatures in most regions, which slightly reduces dehydration stress compared with a summer fast. It is not risk-free, and the day's demands still require planning.
Who fasts, who is exempt, and how the rules reconcile
Yom Kippur fasting is framed as an obligation for healthy adults, but Jewish law recognizes exemptions and modifications. The guiding principle in Jewish medical ethics is that preserving life overrides almost every ritual obligation. The thresholds are not one-size-fits-all, and different authorities weigh them differently.
Children below bar/bat mitzvah age are generally not obligated to complete a full fast; some practice partial fasting as training. People who are ill, including those with active infection or significant acute symptoms, are commonly advised not to fast. Pregnant and nursing individuals often receive case-by-case guidance, sometimes involving modified or partial fasting. People taking medications that must be timed or taken with food need individualized coordination. Those with diabetes, kidney disease, or heart conditions require prior medical input, not in-the-moment improvisation.
The reconciliation of thresholds is where people get confused. Three separate judgments apply at once: the religious obligation (set by halachic authorities), the medical risk (set by the individual's condition and clinician), and the community's published times (set by local custom). These can disagree. The working rule is that the most protective judgment governs a health question, and the local rabbi resolves religious specifics.
A counterintuitive detail worth flagging: complete abstention is not always the safest or most devout-seeming choice. For some conditions, a structured partial fast with fluids, or shifting medication timing, is more appropriate than a "brave" full fast. Wild improvisation at the last minute is the real hazard.
Common misconceptions about the date and the day
One frequent error is treating Yom Kippur as a single midnight-to-midnight date. It is not. The holiday named "2026" begins on the evening of September 20 and ends the night of September 21, and the daytime of September 21 is the heart of the observance.
A second misconception is that the date moves randomly. It does not; it cycles predictably through the 19-year leap pattern. That is why you can look ahead and find Yom Kippur in early September in some years and early October in others. The 2026 date is on the earlier side of that range.
A third is the belief that all fasts run exactly 24 hours. The Hebrew day's sunset-to-nightfall design adds time at both ends, producing roughly 25 hours. A fourth is that fasting is required of everyone without exception; exemptions exist and are honored, not loopholes.
People also confuse Yom Kippur with Rosh Hashanah's length and character. Rosh Hashanah spans two days and has its own customs; Yom Kippur is a single 25-hour day with a distinct liturgy and five specific afflictions beyond food and water traditional to the day. And a final misconception: the Gregorian date "September 20, 2026" is the start of the observance, not the whole of it. Search snippets that show only one date can mislead.
Practical preparation for September 2026
Planning ahead converts a demanding fast into a manageable one. The steps below are general and non-prescriptive; individual medical decisions belong with a clinician. Always confirm exact start and end times with your own community's published zmanim rather than relying on a generic table.
Confirm your synagogue's or community's candle-lighting and fast-ending times for September 20-21, 2026, since these override any calculator. Discuss medication scheduling and any chronic condition with your clinician and rabbi in the weeks before, not on the eve. Hydrate normally in the days prior and avoid a last-minute heavy meal that can worsen discomfort. Plan a light, gentle break-fast after nightfall rather than a large immediate feast. Arrange childcare, work coverage, and travel so the day is protected from avoidable stress. Know where to get help if someone becomes dizzy, faint, or confused during the fast.
The red-flag warnings are unambiguous and deserve attention. Seek medical help if a faster develops fainting, chest pain, confusion, very dark or absent urine, or persistent vomiting. These are not normal fast symptoms. Children, older adults, and people with chronic illness have narrower margins, so err toward caution.
Limits of any date guide, and a final caution
A date guide can tell you when Yom Kippur 2026 falls and roughly how the 25 hours unfold. It cannot tell you your community's exact times, which depend on local custom and halachic rulings. It cannot assess your personal fast fitness, which is a medical question. And it cannot resolve the boundary cases where religious and medical thresholds pull in different directions.
The calendar calculation itself is reliable to a day, but clock times are estimates. Twilight definitions vary. Some authorities end the fast at a different dusk stage than others. The result is that two synagogues in the same city can post end times a few minutes apart, and both can be correct within their own tradition. Plan around your own community's numbers.
High-latitude readers face the widest uncertainty, because twilight can be long and the differences between definitions grow. If you live far north or south, consult local guidance early rather than extrapolating from a US city table.
This article is general educational information about calendar timing and fasting physiology. It is not medical advice, a diagnosis, or a treatment plan, and it cannot determine whether you should fast. Fasting decisions for anyone with a health condition, and any medication timing, should be made with a qualified local clinician and, where relevant, a rabbi. If someone shows danger signs during a fast, contact local emergency services immediately.