Week 40, 2026
September 28 – October 4, 2026
Monday September 28 – Sunday October 42026-W40Days 271–277
The seven days
| Date | ISO week date | Day of year | US week | Islamic date (computed) | Holidays and other dates |
|---|---|---|---|---|---|
| Mon, Sep 28 | 2026-W40-1 | 271 | 40 | 17 Rabi' al-Thani 1448 AH | King's Birthday (Australia: Western Australia) |
| Tue, Sep 29 | 2026-W40-2 | 272 | 40 | 18 Rabi' al-Thani 1448 AH | |
| Wed, Sep 30 | 2026-W40-3 | 273 | 40 | 19 Rabi' al-Thani 1448 AH | National Day for Truth and Reconciliation (Canada (federal)) |
| Thu, Oct 1 | 2026-W40-4 | 274 | 40 | 20 Rabi' al-Thani 1448 AH | National Day (Hong Kong) |
| Fri, Oct 2 | 2026-W40-5 | 275 | 40 | 21 Rabi' al-Thani 1448 AH | |
| Sat, Oct 3 | 2026-W40-6 | 276 | 40 | 22 Rabi' al-Thani 1448 AH | |
| Sun, Oct 4 | 2026-W40-7 | 277 | 41 | 23 Rabi' al-Thani 1448 AH |
About week 40
The week spans two months: it starts in September and ends in October, with October 1 on Thursday, the first day of Q4. In US numbering, where weeks start on Sunday and the week of January 1 is week 1, Monday to Saturday are US week 40 and Sunday US week 41.
Holidays this week: King's Birthday on Mon, Sep 28 in Australia: Western Australia; National Day for Truth and Reconciliation on Wed, Sep 30 in Canada (federal); National Day on Thu, Oct 1 in Hong Kong. On Sun, Oct 4 clocks in South-east Australia (Sydney, Melbourne) go forward one hour at 2:00 a.m. All weeks of 2026 lists the neighbouring weeks.
Week 40 in other years
| Year | Week 40 runs |
|---|---|
| 2024 | Mon, Sep 30 – Sun, Oct 6 |
| 2025 | Mon, Sep 29 – Sun, Oct 5 |
| 2026 | Mon, Sep 28 – Sun, Oct 4 |
| 2027 | Mon, Oct 4 – Sun, Oct 10 |
| 2028 | Mon, Oct 2 – Sun, Oct 8 |
| 2029 | Mon, Oct 1 – Sun, Oct 7 |
In 2027, week 40 runs Mon, Oct 4 – Sun, Oct 10: 2026 has 53 weeks, so the same number comes 371 days later, 6 days later in the calendar. Over the 400-year cycle, the Monday of week 40 falls between September 27 and October 4.
By the end of week 40, 277 days of 2026 have passed (75.9% of the year), and 13 ISO weeks of 2026 remain. The week falls in Q3.
Writing week 40
ISO 8601 writes this week as 2026-W40 (basic format 2026W40), from 2026-W40-1 on Monday to -7 on Sunday. The week number page shows the spreadsheet and Python formulas that give these numbers.