Why do you list Sunday 27th September 2026, as a High Holy Day, when Leviticus 23 v 37, clearly states - ' every thing accprding to its day' - indicating that the day and days following the High Holy Day, of 25th/26t, are not be observed as Sabbath Days?

Thanks for writing in. Sunday 27 September 2026 is 16 Tishrei 5787 — the second day of Sukkot. (Sukkot begins at sundown on the 25th, with the first day falling on Saturday the 26th.)

The reason it's marked is that Hebcal defaults to the Diaspora calendar, where the second day of a festival is observed as Yom Tov Sheni shel Galuyot. This is a rabbinic practice rather than a Torah one, and it originated in the era when the new month was declared by witnesses in Jerusalem and communities far from the Land couldn't be certain which day had been fixed — so they kept two. It was retained by rabbinic decree even after the calendar became mathematically fixed.

In the Land of Israel, 16 Tishrei is not a festival day at all — it's Chol HaMoed, an intermediate day of Sukkot. If you'd prefer a calendar that reflects that, you can switch to the Israel schedule on our custom calendar page, and 27 September will show as Chol HaMoed rather than a festival day.

To be clear about what Hebcal is: we're a calendar that reflects how the Jewish calendar is observed in practice, and we don't take a position on questions of scriptural interpretation. The Israel/Diaspora setting is there precisely because observance differs, and we'd rather give you the option than decide for you.