Week 39 of 2025 runs September 22, 2025 to September 28, 2025.
Week 39 starts on Monday, September 22, 2025 and ends on Sunday, September 28, 2025. It's the 265th day of the year, sits in Q3, and falls in September. By the end of this week, 271 of 365 days are gone, putting 2025 at 74.2%.
There are no public holidays this week, so all 5 weekdays are working days. Need a different week? Browse the full 2025 week calendar, or jump to this week's number.
Week 39 at a glance
The 7 days of week 39
Every date in week 39 of 2025, Monday through Sunday, with day-of-year numbers and events.
| Day | Date | Day no. | Type | Events |
|---|---|---|---|---|
| Monday | Day 265 | Weekday | Autumn Equinox | |
| Tuesday | Day 266 | Weekday | ||
| Wednesday | Day 267 | Weekday | ||
| Thursday | Day 268 | Weekday | ||
| Friday | Day 269 | Weekday | ||
| Saturday | Day 270 | Weekend | ||
| Sunday | Day 271 | Weekend |
What week 39 of 2025 means
ISO 8601 numbers weeks so every week starts on Monday and ends on Sunday. Week 1 is the one holding the year's first Thursday, which is why early January can land in week 52 or 53 of the previous year. Week 39 is one piece of that system.
In 2025, week 39 covers Sep 22 – Sep 28, 2025. That's September, deep in Q3. The same week number shifts by a day or two each year, so week 39 in 2026 won't share these exact dates. The table below shows how it moves.
Want to check a specific date instead of a week number? The week calculator converts any date to its ISO week. Curious how many weeks a year holds? The weeks in a year guide explains 52 versus 53. And the ISO week number page covers the standard end to end.
Holidays in week 39 of 2025
🇺🇸 United States
🇬🇧 United Kingdom
🇨🇦 Canada
🇦🇺 Australia
Week 39 across years
The same ISO week number lands on different dates each year. Here's how week 39 shifts.
Week 39 of 2025: questions and answers
What days are in week 39 of 2025?
Week 39 of 2025 runs from September 22, 2025 (Monday) through September 28, 2025 (Sunday). It spans September.
What month is week 39 in 2025?
Week 39 of 2025 falls entirely in September 2025.
How many working days are in week 39 of 2025?
Week 39 of 2025 has 5 working days.
What week is Autumn Equinox in 2025?
Autumn Equinox falls in ISO week 39 of 2025 (Sep 22 – Sep 28, 2025).
What quarter is week 39 of 2025 in?
Week 39 of 2025 is in Q3 (2025). The week starts on day 265 of 365.
What is ISO week 39?
ISO week 39 is defined by the ISO 8601 international standard. It begins on Monday, September 22, 2025, and ends on Sunday, September 28, 2025. It is week 75% through the ISO year 2025.