Ever wonder why your Jewish friends suddenly disappear for two days in the middle of September, or sometimes early October? It’s not like they’re trying to be mysterious. It’s just that the Hebrew calendar is a bit of a moving target.
If you’re trying to pin down when is Rosh Hashanah celebrated, the short answer is that it starts at sundown on the eve of the 1st of Tishrei. But because the Jewish calendar follows the moon, that date jumps around the secular calendar like crazy.
The Dates for Rosh Hashanah (2025–2027)
Planning ahead? Good luck doing that without a specific chart. In the secular world, we’re used to New Year’s Eve being December 31st every single time. Simple. But the "Head of the Year" doesn't play by those rules.
For 2025, the holiday kicks off at sundown on Monday, September 22, and wraps up at nightfall on Wednesday, September 24.
Fast forward to 2026. When is Rosh Hashanah celebrated then? It starts Friday evening, September 11, and goes until Sunday evening, September 13. Notice the shift? That’s nearly a two-week difference.
In 2027, it pushes even later. You’re looking at sundown on Friday, October 1, through nightfall on Sunday, October 3.
Why the Date Always Changes
Honestly, the "why" is where it gets interesting. The Jewish calendar is lunisolar. Most of the world uses the Gregorian calendar, which is strictly solar—365 days, give or take a leap year. The Hebrew calendar, however, tries to keep the months aligned with the moon cycles while keeping the seasons aligned with the sun.
It’s basically a massive math puzzle that ancient sages solved centuries ago.
A lunar month is roughly 29.5 days. If you just had 12 lunar months, your year would only be about 354 days long. You'd lose 11 days every year. Pretty soon, you’d be celebrating the "autumn" harvest in the middle of a blizzard. To fix this, the Hebrew calendar adds an entire extra month—Adar II—seven times every 19 years.
✨ Don't miss: 63.5 Inches to cm: Why This Specific Measurement Pops Up Everywhere
The "Day of the Week" Problem
There's also a rule called Lo Adu Rosh. It sounds like a secret code, but it's basically a scheduling safeguard.
Rosh Hashanah is never allowed to start on a Sunday, Wednesday, or Friday. Why? Because if Rosh Hashanah fell on those days, it would cause other holidays like Yom Kippur or Hoshanah Rabbah to fall on days that would make it impossible to observe certain rituals (like preparing for the Sabbath). So, if the new moon technically shows up on a Wednesday, the "official" start is bumped a day.
It's Not Just One Day (Even in Israel)
Here’s a nuance that trips people up. Most Jewish holidays are celebrated for one day in Israel and two days in the "Diaspora" (everywhere else). This started back in ancient times when news was carried by foot or fire signals. People far away weren't sure when the new moon was sighted in Jerusalem, so they doubled up just to be safe.
But Rosh Hashanah is different.
Even in Israel, it’s two days. The Sages call it Yoma Arichta, which literally means "one long day." Because it falls on the first day of the month, even the folks in Jerusalem sometimes didn't get the official word from the moon-watchers until late in the day. To avoid the stress of a last-minute holiday, they just made the whole 48-hour period sacred.
The Sunset Start
You’ve probably noticed that all these dates say "at sundown." In Jewish tradition, the day doesn't start at midnight. It starts when the sun goes down. This comes straight from the first chapter of Genesis: "And there was evening and there was morning, one day."
So, if you see a calendar that says Rosh Hashanah is September 12th, you actually need to be ready to start the party on the evening of the 11th.
What Actually Happens During Those Two Days?
It's not all about the calendar math. This is a "High Holy Day," which means it’s a heavy-hitter on the spiritual scale. While January 1st is usually about parties and champagne, Rosh Hashanah is more about "spiritual accounting."
- The Shofar Blasts: You’ll hear a ram’s horn blown in the synagogue. It’s loud, it’s piercing, and it’s meant to be a wake-up call for the soul.
- Apples and Honey: This is the big one for the kids (and let’s be real, the adults too). You dip apple slices in honey to symbolize a wish for a "sweet" new year.
- Tashlich: On the first afternoon, people often walk to a body of water—a river, a lake, even a creek—to symbolically "cast off" their sins by throwing bread crumbs or just shaking out their pockets.
- The Round Challah: Usually, Challah bread is braided in a long loaf. On Rosh Hashanah, it’s baked into a circle to represent the cycle of the year and the crown of God.
Common Misconceptions About the Timing
People often think Rosh Hashanah is the "first month" of the year. Technically, Tishrei is the seventh month. Wait, what?
It’s kinda like the fiscal year vs. the calendar year. In the Torah, the month of Nissan (in the spring) is considered the first month because that’s when the Exodus happened. But Rosh Hashanah is the New Year for years—it’s when the "year number" actually clicks over. Think of it as the anniversary of the creation of humanity.
🔗 Read more: Types of Engagement Ring Settings: What Your Jeweler Isn’t Telling You
Another weird thing? If Rosh Hashanah falls on a Saturday (Shabbat), the Shofar isn't blown on that day. You have to wait until the second day to hear it. It's a precaution to make sure nobody accidentally carries the heavy horn through a public area, which is a no-no on the Sabbath.
Actionable Next Steps
Now that you know when is Rosh Hashanah celebrated and why the dates are so weird, you can actually plan for it without getting blindsided by a random Tuesday in September.
- Check the Sundown Times: If you're hosting or attending a dinner, look up the exact sunset time for your specific zip code. "Sundown" in New York is different from "Sundown" in Los Angeles.
- Sync Your Digital Calendar: Don't rely on your brain. Most Google or Outlook calendars have an "alternate calendar" setting where you can toggle on "Jewish Holidays." It will automatically update for the leap years.
- Order Your Honey Early: If you’re going for the fancy artisanal stuff, do it a month out. The rush for local honey gets real the week before Tishrei.
- Bridge the Gap: Remember that Rosh Hashanah is just the start. It kicks off the "Ten Days of Repentance," leading straight into Yom Kippur. If you're marking your calendar, mark both.
Whether you're celebrating or just trying to be a respectful neighbor, knowing the rhythm of these two days helps make sense of why the Jewish year starts with such a specific, lunar-driven bang.