Week 51, 2027
December 20–26, 2027
Monday December 20 – Sunday December 262027-W51Days 354–360
The seven days
| Date | ISO week date | Day of year | US week | Islamic date (computed) | Holidays and other dates |
|---|---|---|---|---|---|
| Mon, Dec 20 | 2027-W51-1 | 354 | 52 | 22 Rajab 1449 AH | |
| Tue, Dec 21 | 2027-W51-2 | 355 | 52 | 23 Rajab 1449 AH | |
| Wed, Dec 22 | 2027-W51-3 | 356 | 52 | 24 Rajab 1449 AH | |
| Thu, Dec 23 | 2027-W51-4 | 357 | 52 | 25 Rajab 1449 AH | |
| Fri, Dec 24 | 2027-W51-5 | 358 | 52 | 26 Rajab 1449 AH | Christmas Day (observed) (United States (federal)); Christmas Eve (6pm to midnight) (Australia: Queensland); Christmas Eve |
| Sat, Dec 25 | 2027-W51-6 | 359 | 52 | 27 Rajab 1449 AH | Christmas Day (11 sets); Hanukkah (first day) |
| Sun, Dec 26 | 2027-W51-7 | 360 | 53 | 28 Rajab 1449 AH | Boxing Day (5 sets); Saint Stephen's Day (Ireland) |
About week 51
In US numbering, where weeks start on Sunday and the week of January 1 is week 1, Monday to Saturday are US week 52 and Sunday US week 53.
Holidays this week: Christmas Day (observed) on Fri, Dec 24 in United States (federal); Christmas Eve (6pm to midnight) on Fri, Dec 24 in Australia: Queensland; Christmas Day on Sat, Dec 25 in 11 of the countries and regions we cover; Boxing Day on Sun, Dec 26 in 5 of the countries and regions we cover; Saint Stephen's Day on Sun, Dec 26 in Ireland. The December solstice is on Wed, Dec 22 at 02:42 UTC. Also this week: Christmas Eve on Fri, Dec 24 (December 24); Hanukkah (first day) on Sat, Dec 25 (25 Kislev; the first candle is lit the evening before). All weeks of 2027 lists the neighbouring weeks.
Week 51 in other years
| Year | Week 51 runs |
|---|---|
| 2025 | Mon, Dec 15 – Sun, Dec 21 |
| 2026 | Mon, Dec 14 – Sun, Dec 20 |
| 2027 | Mon, Dec 20 – Sun, Dec 26 |
| 2028 | Mon, Dec 18 – Sun, Dec 24 |
| 2029 | Mon, Dec 17 – Sun, Dec 23 |
| 2030 | Mon, Dec 16 – Sun, Dec 22 |
In 2028, week 51 runs Mon, Dec 18 – Sun, Dec 24: 364 days later, 2 days earlier in the calendar. Over the 400-year cycle, the Monday of week 51 falls between December 13 and December 20.
By the end of week 51, 360 days of 2027 have passed (98.6% of the year), and 1 ISO week of 2027 remain. The week falls in Q4.
Writing week 51
ISO 8601 writes this week as 2027-W51 (basic format 2027W51), from 2027-W51-1 on Monday to -7 on Sunday. The week number page shows the spreadsheet and Python formulas that give these numbers.