| Altdorf Williamstown | Eastern Australia Time | -08:00 |
| Altdorf Willoughby | Eastern Australia Time | -08:00 |
| Altdorf Willisau | Central European Time | 00:00 |
| Altdorf Williston Park | Eastern Time | 06:00 |
| Altdorf Willits | Pacific Time | 09:00 |
| Altdorf Willaston | United Kingdom Time | 01:00 |
| Altdorf Wilkesboro | Eastern Time | 06:00 |
| Altdorf Williams | Mountain Time | 09:00 |
| Altdorf Williamsburg | Eastern Time | 06:00 |
| Altdorf Wiesbaden | Central European Time | 00:00 |
| Altdorf Wieselburg | Central European Time | 00:00 |
| Altdorf Wildwood | Eastern Time | 06:00 |
| Altdorf Wilkau-Haßlau | Central European Time | 00:00 |
| Altdorf Wilbraham | Eastern Time | 06:00 |
| Altdorf Wildau | Central European Time | 00:00 |
| Altdorf Wilder | Eastern Time | 06:00 |
| Altdorf Wilderswil | Central European Time | 00:00 |
| Altdorf Wickham | United Kingdom Time | 01:00 |
| Altdorf Wickham Bishops | United Kingdom Time | 01:00 |
| Altdorf Wicklow | Ireland Time | 01:00 |
| Altdorf Widnau | Central European Time | 00:00 |
| Altdorf Vosselaar | Central European Time | 00:00 |
| Altdorf Whitney | Central Time | 07:00 |
| Altdorf Vostochny District | Moscow Time | -01:00 |
| Altdorf Three Rivers | Eastern Time | 06:00 |
| Altdorf Threlkeld | United Kingdom Time | 01:00 |
| Altdorf Thriprayar | India Standard Time | -03:30 |
| Altdorf Thrissur | India Standard Time | -03:30 |
| Altdorf Thornbury | United Kingdom Time | 01:00 |
| Altdorf Thornleigh | Eastern Australia Time | -08:00 |
| Altdorf Thompsonville | Eastern Time | 06:00 |
| Altdorf Thong Nian | Indochina Time | -05:00 |
| Altdorf Thornton | Eastern Time | 06:00 |
| Altdorf Thurso | United Kingdom Time | 01:00 |
| Altdorf Thusis | Central European Time | 00:00 |
| Altdorf Tianjin | China Time | -06:00 |
| Altdorf Thung Song | Indochina Time | -05:00 |
| Altdorf Thuckalay | India Standard Time | -03:30 |
| Altdorf Thousand Palms | Pacific Time | 09:00 |
| Altdorf Thiruverumbur | India Standard Time | -03:30 |
| Altdorf Thodupuzha | India Standard Time | -03:30 |
| Altdorf Thoothukudi | India Standard Time | -03:30 |
| Altdorf Thoppur | India Standard Time | -03:30 |
| Altdorf Thorley | United Kingdom Time | 01:00 |
| Altdorf Thirupathi | India Standard Time | -03:30 |
| Altdorf Thirroul | Eastern Australia Time | -08:00 |
| Altdorf Tacloban City | Philippine Time | -06:00 |
| Altdorf Thibodaux | Central Time | 07:00 |
| Altdorf Thị xã Phú Thọ | Indochina Time | -05:00 |
| Altdorf Ujire | India Standard Time | -03:30 |