What Day of the Week Is September 21?
September 21, 2027 falls on a Tuesday. This year, September 21, 2026 was a Monday.
It is day 264 of 2027, and 101 days of the year come after it. The date sits in ISO week 38 and in the third quarter, July to September. North of the equator it is day 93 of summer, and fall starts on September 23. In Australia and the rest of the south, it is winter. The Moon is a waning gibbous that day, and the next full moon is on Friday, October 15, 2027. It is not a US federal holiday.
September 21 from 2025 to 2028
The same date in four years, side by side. Moon phases use US Eastern dates.
| Fact | 2025 | 2026 | 2027 | 2028 |
|---|---|---|---|---|
| Day of the week | Sunday | Monday | Tuesday | Thursday |
| Day of the year | 264 of 365 | 264 of 365 | 264 of 365 | 265 of 366 |
| Days left in the year | 101 | 101 | 101 | 101 |
| ISO week | 38 | 39 | 38 | 38 |
| Quarter | Q3 | Q3 | Q3 | Q3 |
| Season (north) | Day 94 of summer | Day 93 of summer | Day 93 of summer | Day 94 of summer |
| Moon (US Eastern) | New moon | Waxing gibbous | Waning gibbous | Waxing crescent |
| US federal holiday | No | No | No | No |
| Other holidays | International Day of Peace | Yom Kippur, International Day of Peace | International Day of Peace | Rosh Hashanah, International Day of Peace |
Holidays on September 21
Every year, September 21 is International Day of Peace.
Holidays that move with the calendar land on September 21 in some years from 2026 to 2035.
| Holiday or observance | Years on September 21 |
|---|---|
| Rosh Hashanah | 2028 |
| Yom Kippur | 2026 |
| Oktoberfest | 2030 |
Born on September 21
In most horoscope tables, September 21 falls under Virgo, the sign that runs from August 23 to September 22.
The birthstone for September is the sapphire on the American Gem Society list.
September 21 every year from 1950 to 2049
Find the decade on the left, then the last digit of the year across the top. A baby born on September 21, 1990 arrived on a Friday, and one born on September 21, 2000 on a Thursday. Weekends are shaded.
| Years | …0 | …1 | …2 | …3 | …4 | …5 | …6 | …7 | …8 | …9 |
|---|---|---|---|---|---|---|---|---|---|---|
| 1950s | Thu | Fri | Sun | Mon | Tue | Wed | Fri | Sat | Sun | Mon |
| 1960s | Wed | Thu | Fri | Sat | Mon | Tue | Wed | Thu | Sat | Sun |
| 1970s | Mon | Tue | Thu | Fri | Sat | Sun | Tue | Wed | Thu | Fri |
| 1980s | Sun | Mon | Tue | Wed | Fri | Sat | Sun | Mon | Wed | Thu |
| 1990s | Fri | Sat | Mon | Tue | Wed | Thu | Sat | Sun | Mon | Tue |
| 2000s | Thu | Fri | Sat | Sun | Tue | Wed | Thu | Fri | Sun | Mon |
| 2010s | Tue | Wed | Fri | Sat | Sun | Mon | Wed | Thu | Fri | Sat |
| 2020s | Mon | Tue | Wed | Thu | Sat | Sun | Mon | Tue | Thu | Fri |
| 2030s | Sat | Sun | Tue | Wed | Thu | Fri | Sun | Mon | Tue | Wed |
| 2040s | Fri | Sat | Sun | Mon | Wed | Thu | Fri | Sat | Mon | Tue |
When September 21 is on the same weekday again
After 2027, September 21 is next a Tuesday in 2032. The next weekend September 21 is in 2030, on a Saturday.
| Day of the week | Next year after 2027 |
|---|---|
| Monday | 2037 |
| Tuesday | 2032 |
| Wednesday | 2033 |
| Thursday | 2028 |
| Friday | 2029 |
| Saturday | 2030 |
| Sunday | 2031 |
September 21 by year
| Year | Day of the week | Weekend or weekday |
|---|---|---|
| 2023 | Thursday | Weekday |
| 2024 | Saturday | Weekend |
| 2025 | Sunday | Weekend |
| 2026 | Monday | Weekday |
| 2027 | Tuesday | Weekday |
| 2028 | Thursday | Weekday |
| 2029 | Friday | Weekday |
| 2030 | Saturday | Weekend |
| 2031 | Sunday | Weekend |
| 2032 | Tuesday | Weekday |
| 2033 | Wednesday | Weekday |
| 2034 | Thursday | Weekday |
Why the weekday changes
A common year is 365 days, one day more than 52 weeks. So September 21 moves on one weekday each year: Monday in 2026, Tuesday in 2027. The jump is two days when February 29 comes in between, so September 21, 2028 is a Thursday, two on from 2027's Tuesday. Between 1901 and 2099, the whole pattern repeats every 28 years.
More about September 21 on this site
September 21 questions
What day of the week is September 21, 2027?
September 21, 2027 is a Tuesday. It is day 264 of the year and falls in ISO week 38.
Is September 21 a holiday?
Every year, September 21 is International Day of Peace. September 21, 2027 is not a US federal holiday.
Cite this page
APA: ClockTotals. (2026, October 28). What Day of the Week Is September 21? https://clocktotals.com/what-day-is/september-21/
MLA: “What Day of the Week Is September 21?” ClockTotals, 28 Oct. 2026, clocktotals.com/what-day-is/september-21/.
Link (HTML): <a href="https://clocktotals.com/what-day-is/september-21/">What Day of the Week Is September 21?</a>