settimezone - Configuración de la zona horaria en UTC(0) en PHP

timezone america buenos aires

Question

¿Por qué funciona esto?

date_default_timezone_set(''Australia/Currie'');

Pero esto no parece tener ningún efecto en absoluto?

date_default_timezone_set(''UTC'');

Este valor no cambia al configurar la zona horaria a UTC:

echo date(''Y-m-d H:i:s'', time());

Estoy usando php 5.2.13, y la zona horaria de mi servidor es:

$server_tz = date_default_timezone_get();
echo $server_tz; //outputs ''America/Guayaquil''

Este es el código original:

echo time() . "<br>/n";
date_default_timezone_set(''UTC'');
echo time() . "<br>/n";

Salida:

1317235130
1317235130

Answer 1

Lista de zonas horarias completas disponibles.

$time_zones = array (
0 => ''Africa/Abidjan'',
1 => ''Africa/Accra'',
2 => ''Africa/Addis_Ababa'',
3 => ''Africa/Algiers'',
4 => ''Africa/Asmara'',
5 => ''Africa/Asmera'',
6 => ''Africa/Bamako'',
7 => ''Africa/Bangui'',
8 => ''Africa/Banjul'',
9 => ''Africa/Bissau'',
10 => ''Africa/Blantyre'',
11 => ''Africa/Brazzaville'',
12 => ''Africa/Bujumbura'',
13 => ''Africa/Cairo'',
14 => ''Africa/Casablanca'',
15 => ''Africa/Ceuta'',
16 => ''Africa/Conakry'',
17 => ''Africa/Dakar'',
18 => ''Africa/Dar_es_Salaam'',
19 => ''Africa/Djibouti'',
20 => ''Africa/Douala'',
21 => ''Africa/El_Aaiun'',
22 => ''Africa/Freetown'',
23 => ''Africa/Gaborone'',
24 => ''Africa/Harare'',
25 => ''Africa/Johannesburg'',
26 => ''Africa/Juba'',
27 => ''Africa/Kampala'',
28 => ''Africa/Khartoum'',
29 => ''Africa/Kigali'',
30 => ''Africa/Kinshasa'',
31 => ''Africa/Lagos'',
32 => ''Africa/Libreville'',
33 => ''Africa/Lome'',
34 => ''Africa/Luanda'',
35 => ''Africa/Lubumbashi'',
36 => ''Africa/Lusaka'',
37 => ''Africa/Malabo'',
38 => ''Africa/Maputo'',
39 => ''Africa/Maseru'',
40 => ''Africa/Mbabane'',
41 => ''Africa/Mogadishu'',
42 => ''Africa/Monrovia'',
43 => ''Africa/Nairobi'',
44 => ''Africa/Ndjamena'',
45 => ''Africa/Niamey'',
46 => ''Africa/Nouakchott'',
47 => ''Africa/Ouagadougou'',
48 => ''Africa/Porto-Novo'',
49 => ''Africa/Sao_Tome'',
50 => ''Africa/Timbuktu'',
51 => ''Africa/Tripoli'',
52 => ''Africa/Tunis'',
53 => ''Africa/Windhoek'',
54 => ''America/Adak'',
55 => ''America/Anchorage'',
56 => ''America/Anguilla'',
57 => ''America/Antigua'',
58 => ''America/Araguaina'',
59 => ''America/Argentina/Buenos_Aires'',
60 => ''America/Argentina/Catamarca'',
61 => ''America/Argentina/ComodRivadavia'',
62 => ''America/Argentina/Cordoba'',
63 => ''America/Argentina/Jujuy'',
64 => ''America/Argentina/La_Rioja'',
65 => ''America/Argentina/Mendoza'',
66 => ''America/Argentina/Rio_Gallegos'',
67 => ''America/Argentina/Salta'',
68 => ''America/Argentina/San_Juan'',
69 => ''America/Argentina/San_Luis'',
70 => ''America/Argentina/Tucuman'',
71 => ''America/Argentina/Ushuaia'',
72 => ''America/Aruba'',
73 => ''America/Asuncion'',
74 => ''America/Atikokan'',
75 => ''America/Atka'',
76 => ''America/Bahia'',
77 => ''America/Bahia_Banderas'',
78 => ''America/Barbados'',
79 => ''America/Belem'',
80 => ''America/Belize'',
81 => ''America/Blanc-Sablon'',
82 => ''America/Boa_Vista'',
83 => ''America/Bogota'',
84 => ''America/Boise'',
85 => ''America/Buenos_Aires'',
86 => ''America/Cambridge_Bay'',
87 => ''America/Campo_Grande'',
88 => ''America/Cancun'',
89 => ''America/Caracas'',
90 => ''America/Catamarca'',
91 => ''America/Cayenne'',
92 => ''America/Cayman'',
93 => ''America/Chicago'',
94 => ''America/Chihuahua'',
95 => ''America/Coral_Harbour'',
96 => ''America/Cordoba'',
97 => ''America/Costa_Rica'',
98 => ''America/Creston'',
99 => ''America/Cuiaba'',
100 => ''America/Curacao'',
101 => ''America/Danmarkshavn'',
102 => ''America/Dawson'',
103 => ''America/Dawson_Creek'',
104 => ''America/Denver'',
105 => ''America/Detroit'',
106 => ''America/Dominica'',
107 => ''America/Edmonton'',
108 => ''America/Eirunepe'',
109 => ''America/El_Salvador'',
110 => ''America/Ensenada'',
111 => ''America/Fort_Nelson'',
112 => ''America/Fort_Wayne'',
113 => ''America/Fortaleza'',
114 => ''America/Glace_Bay'',
115 => ''America/Godthab'',
116 => ''America/Goose_Bay'',
117 => ''America/Grand_Turk'',
118 => ''America/Grenada'',
119 => ''America/Guadeloupe'',
120 => ''America/Guatemala'',
121 => ''America/Guayaquil'',
122 => ''America/Guyana'',
123 => ''America/Halifax'',
124 => ''America/Havana'',
125 => ''America/Hermosillo'',
126 => ''America/Indiana/Indianapolis'',
127 => ''America/Indiana/Knox'',
128 => ''America/Indiana/Marengo'',
129 => ''America/Indiana/Petersburg'',
130 => ''America/Indiana/Tell_City'',
131 => ''America/Indiana/Vevay'',
132 => ''America/Indiana/Vincennes'',
133 => ''America/Indiana/Winamac'',
134 => ''America/Indianapolis'',
135 => ''America/Inuvik'',
136 => ''America/Iqaluit'',
137 => ''America/Jamaica'',
138 => ''America/Jujuy'',
139 => ''America/Juneau'',
140 => ''America/Kentucky/Louisville'',
141 => ''America/Kentucky/Monticello'',
142 => ''America/Knox_IN'',
143 => ''America/Kralendijk'',
144 => ''America/La_Paz'',
145 => ''America/Lima'',
146 => ''America/Los_Angeles'',
147 => ''America/Louisville'',
148 => ''America/Lower_Princes'',
149 => ''America/Maceio'',
150 => ''America/Managua'',
151 => ''America/Manaus'',
152 => ''America/Marigot'',
153 => ''America/Martinique'',
154 => ''America/Matamoros'',
155 => ''America/Mazatlan'',
156 => ''America/Mendoza'',
157 => ''America/Menominee'',
158 => ''America/Merida'',
159 => ''America/Metlakatla'',
160 => ''America/Mexico_City'',
161 => ''America/Miquelon'',
162 => ''America/Moncton'',
163 => ''America/Monterrey'',
164 => ''America/Montevideo'',
165 => ''America/Montreal'',
166 => ''America/Montserrat'',
167 => ''America/Nassau'',
168 => ''America/New_York'',
169 => ''America/Nipigon'',
170 => ''America/Nome'',
171 => ''America/Noronha'',
172 => ''America/North_Dakota/Beulah'',
173 => ''America/North_Dakota/Center'',
174 => ''America/North_Dakota/New_Salem'',
175 => ''America/Ojinaga'',
176 => ''America/Panama'',
177 => ''America/Pangnirtung'',
178 => ''America/Paramaribo'',
179 => ''America/Phoenix'',
180 => ''America/Port-au-Prince'',
181 => ''America/Port_of_Spain'',
182 => ''America/Porto_Acre'',
183 => ''America/Porto_Velho'',
184 => ''America/Puerto_Rico'',
185 => ''America/Rainy_River'',
186 => ''America/Rankin_Inlet'',
187 => ''America/Recife'',
188 => ''America/Regina'',
189 => ''America/Resolute'',
190 => ''America/Rio_Branco'',
191 => ''America/Rosario'',
192 => ''America/Santa_Isabel'',
193 => ''America/Santarem'',
194 => ''America/Santiago'',
195 => ''America/Santo_Domingo'',
196 => ''America/Sao_Paulo'',
197 => ''America/Scoresbysund'',
198 => ''America/Shiprock'',
199 => ''America/Sitka'',
200 => ''America/St_Barthelemy'',
201 => ''America/St_Johns'',
202 => ''America/St_Kitts'',
203 => ''America/St_Lucia'',
204 => ''America/St_Thomas'',
205 => ''America/St_Vincent'',
206 => ''America/Swift_Current'',
207 => ''America/Tegucigalpa'',
208 => ''America/Thule'',
209 => ''America/Thunder_Bay'',
210 => ''America/Tijuana'',
211 => ''America/Toronto'',
212 => ''America/Tortola'',
213 => ''America/Vancouver'',
214 => ''America/Virgin'',
215 => ''America/Whitehorse'',
216 => ''America/Winnipeg'',
217 => ''America/Yakutat'',
218 => ''America/Yellowknife'',
219 => ''Antarctica/Casey'',
220 => ''Antarctica/Davis'',
221 => ''Antarctica/DumontDUrville'',
222 => ''Antarctica/Macquarie'',
223 => ''Antarctica/Mawson'',
224 => ''Antarctica/McMurdo'',
225 => ''Antarctica/Palmer'',
226 => ''Antarctica/Rothera'',
227 => ''Antarctica/South_Pole'',
228 => ''Antarctica/Syowa'',
229 => ''Antarctica/Troll'',
230 => ''Antarctica/Vostok'',
231 => ''Arctic/Longyearbyen'',
232 => ''Asia/Aden'',
233 => ''Asia/Almaty'',
234 => ''Asia/Amman'',
235 => ''Asia/Anadyr'',
236 => ''Asia/Aqtau'',
237 => ''Asia/Aqtobe'',
238 => ''Asia/Ashgabat'',
239 => ''Asia/Ashkhabad'',
240 => ''Asia/Baghdad'',
241 => ''Asia/Bahrain'',
242 => ''Asia/Baku'',
243 => ''Asia/Bangkok'',
244 => ''Asia/Beirut'',
245 => ''Asia/Bishkek'',
246 => ''Asia/Brunei'',
247 => ''Asia/Calcutta'',
248 => ''Asia/Chita'',
249 => ''Asia/Choibalsan'',
250 => ''Asia/Chongqing'',
251 => ''Asia/Chungking'',
252 => ''Asia/Colombo'',
253 => ''Asia/Dacca'',
254 => ''Asia/Damascus'',
255 => ''Asia/Dhaka'',
256 => ''Asia/Dili'',
257 => ''Asia/Dubai'',
258 => ''Asia/Dushanbe'',
259 => ''Asia/Gaza'',
260 => ''Asia/Harbin'',
261 => ''Asia/Hebron'',
262 => ''Asia/Ho_Chi_Minh'',
263 => ''Asia/Hong_Kong'',
264 => ''Asia/Hovd'',
265 => ''Asia/Irkutsk'',
266 => ''Asia/Istanbul'',
267 => ''Asia/Jakarta'',
268 => ''Asia/Jayapura'',
269 => ''Asia/Jerusalem'',
270 => ''Asia/Kabul'',
271 => ''Asia/Kamchatka'',
272 => ''Asia/Karachi'',
273 => ''Asia/Kashgar'',
274 => ''Asia/Kathmandu'',
275 => ''Asia/Katmandu'',
276 => ''Asia/Khandyga'',
277 => ''Asia/Kolkata'',
278 => ''Asia/Krasnoyarsk'',
279 => ''Asia/Kuala_Lumpur'',
280 => ''Asia/Kuching'',
281 => ''Asia/Kuwait'',
282 => ''Asia/Macao'',
283 => ''Asia/Macau'',
284 => ''Asia/Magadan'',
285 => ''Asia/Makassar'',
286 => ''Asia/Manila'',
287 => ''Asia/Muscat'',
288 => ''Asia/Nicosia'',
289 => ''Asia/Novokuznetsk'',
290 => ''Asia/Novosibirsk'',
291 => ''Asia/Omsk'',
292 => ''Asia/Oral'',
293 => ''Asia/Phnom_Penh'',
294 => ''Asia/Pontianak'',
295 => ''Asia/Pyongyang'',
296 => ''Asia/Qatar'',
297 => ''Asia/Qyzylorda'',
298 => ''Asia/Rangoon'',
299 => ''Asia/Riyadh'',
300 => ''Asia/Saigon'',
301 => ''Asia/Sakhalin'',
302 => ''Asia/Samarkand'',
303 => ''Asia/Seoul'',
304 => ''Asia/Shanghai'',
305 => ''Asia/Singapore'',
306 => ''Asia/Srednekolymsk'',
307 => ''Asia/Taipei'',
308 => ''Asia/Tashkent'',
309 => ''Asia/Tbilisi'',
310 => ''Asia/Tehran'',
311 => ''Asia/Tel_Aviv'',
312 => ''Asia/Thimbu'',
313 => ''Asia/Thimphu'',
314 => ''Asia/Tokyo'',
315 => ''Asia/Ujung_Pandang'',
316 => ''Asia/Ulaanbaatar'',
317 => ''Asia/Ulan_Bator'',
318 => ''Asia/Urumqi'',
319 => ''Asia/Ust-Nera'',
320 => ''Asia/Vientiane'',
321 => ''Asia/Vladivostok'',
322 => ''Asia/Yakutsk'',
323 => ''Asia/Yekaterinburg'',
324 => ''Asia/Yerevan'',
325 => ''Atlantic/Azores'',
326 => ''Atlantic/Bermuda'',
327 => ''Atlantic/Canary'',
328 => ''Atlantic/Cape_Verde'',
329 => ''Atlantic/Faeroe'',
330 => ''Atlantic/Faroe'',
331 => ''Atlantic/Jan_Mayen'',
332 => ''Atlantic/Madeira'',
333 => ''Atlantic/Reykjavik'',
334 => ''Atlantic/South_Georgia'',
335 => ''Atlantic/St_Helena'',
336 => ''Atlantic/Stanley'',
337 => ''Australia/ACT'',
338 => ''Australia/Adelaide'',
339 => ''Australia/Brisbane'',
340 => ''Australia/Broken_Hill'',
341 => ''Australia/Canberra'',
342 => ''Australia/Currie'',
343 => ''Australia/Darwin'',
344 => ''Australia/Eucla'',
345 => ''Australia/Hobart'',
346 => ''Australia/LHI'',
347 => ''Australia/Lindeman'',
348 => ''Australia/Lord_Howe'',
349 => ''Australia/Melbourne'',
350 => ''Australia/North'',
351 => ''Australia/NSW'',
352 => ''Australia/Perth'',
353 => ''Australia/Queensland'',
354 => ''Australia/South'',
355 => ''Australia/Sydney'',
356 => ''Australia/Tasmania'',
357 => ''Australia/Victoria'',
358 => ''Australia/West'',
359 => ''Australia/Yancowinna'',
360 => ''Europe/Amsterdam'',
361 => ''Europe/Andorra'',
362 => ''Europe/Athens'',
363 => ''Europe/Belfast'',
364 => ''Europe/Belgrade'',
365 => ''Europe/Berlin'',
366 => ''Europe/Bratislava'',
367 => ''Europe/Brussels'',
368 => ''Europe/Bucharest'',
369 => ''Europe/Budapest'',
370 => ''Europe/Busingen'',
371 => ''Europe/Chisinau'',
372 => ''Europe/Copenhagen'',
373 => ''Europe/Dublin'',
374 => ''Europe/Gibraltar'',
375 => ''Europe/Guernsey'',
376 => ''Europe/Helsinki'',
377 => ''Europe/Isle_of_Man'',
378 => ''Europe/Istanbul'',
379 => ''Europe/Jersey'',
380 => ''Europe/Kaliningrad'',
381 => ''Europe/Kiev'',
382 => ''Europe/Lisbon'',
383 => ''Europe/Ljubljana'',
384 => ''Europe/London'',
385 => ''Europe/Luxembourg'',
386 => ''Europe/Madrid'',
387 => ''Europe/Malta'',
388 => ''Europe/Mariehamn'',
389 => ''Europe/Minsk'',
390 => ''Europe/Monaco'',
391 => ''Europe/Moscow'',
392 => ''Europe/Nicosia'',
393 => ''Europe/Oslo'',
394 => ''Europe/Paris'',
395 => ''Europe/Podgorica'',
396 => ''Europe/Prague'',
397 => ''Europe/Riga'',
398 => ''Europe/Rome'',
399 => ''Europe/Samara'',
400 => ''Europe/San_Marino'',
401 => ''Europe/Sarajevo'',
402 => ''Europe/Simferopol'',
403 => ''Europe/Skopje'',
404 => ''Europe/Sofia'',
405 => ''Europe/Stockholm'',
406 => ''Europe/Tallinn'',
407 => ''Europe/Tirane'',
408 => ''Europe/Tiraspol'',
409 => ''Europe/Uzhgorod'',
410 => ''Europe/Vaduz'',
411 => ''Europe/Vatican'',
412 => ''Europe/Vienna'',
413 => ''Europe/Vilnius'',
414 => ''Europe/Volgograd'',
415 => ''Europe/Warsaw'',
416 => ''Europe/Zagreb'',
417 => ''Europe/Zaporozhye'',
418 => ''Europe/Zurich'',
419 => ''Indian/Antananarivo'',
420 => ''Indian/Chagos'',
421 => ''Indian/Christmas'',
422 => ''Indian/Cocos'',
423 => ''Indian/Comoro'',
424 => ''Indian/Kerguelen'',
425 => ''Indian/Mahe'',
426 => ''Indian/Maldives'',
427 => ''Indian/Mauritius'',
428 => ''Indian/Mayotte'',
429 => ''Indian/Reunion'',
430 => ''Pacific/Apia'',
431 => ''Pacific/Auckland'',
432 => ''Pacific/Bougainville'',
433 => ''Pacific/Chatham'',
434 => ''Pacific/Chuuk'',
435 => ''Pacific/Easter'',
436 => ''Pacific/Efate'',
437 => ''Pacific/Enderbury'',
438 => ''Pacific/Fakaofo'',
439 => ''Pacific/Fiji'',
440 => ''Pacific/Funafuti'',
441 => ''Pacific/Galapagos'',
442 => ''Pacific/Gambier'',
443 => ''Pacific/Guadalcanal'',
444 => ''Pacific/Guam'',
445 => ''Pacific/Honolulu'',
446 => ''Pacific/Johnston'',
447 => ''Pacific/Kiritimati'',
448 => ''Pacific/Kosrae'',
449 => ''Pacific/Kwajalein'',
450 => ''Pacific/Majuro'',
451 => ''Pacific/Marquesas'',
452 => ''Pacific/Midway'',
453 => ''Pacific/Nauru'',
454 => ''Pacific/Niue'',
455 => ''Pacific/Norfolk'',
456 => ''Pacific/Noumea'',
457 => ''Pacific/Pago_Pago'',
458 => ''Pacific/Palau'',
459 => ''Pacific/Pitcairn'',
460 => ''Pacific/Pohnpei'',
461 => ''Pacific/Ponape'',
462 => ''Pacific/Port_Moresby'',
463 => ''Pacific/Rarotonga'',
464 => ''Pacific/Saipan'',
465 => ''Pacific/Samoa'',
466 => ''Pacific/Tahiti'',
467 => ''Pacific/Tarawa'',
468 => ''Pacific/Tongatapu'',
469 => ''Pacific/Truk'',
470 => ''Pacific/Wake'',
471 => ''Pacific/Wallis'',
472 => ''Pacific/Yap'',
473 => ''Brazil/Acre'',
474 => ''Brazil/DeNoronha'',
475 => ''Brazil/East'',
476 => ''Brazil/West'',
477 => ''Canada/Atlantic'',
478 => ''Canada/Central'',
479 => ''Canada/East-Saskatchewan'',
480 => ''Canada/Eastern'',
481 => ''Canada/Mountain'',
482 => ''Canada/Newfoundland'',
483 => ''Canada/Pacific'',
484 => ''Canada/Saskatchewan'',
485 => ''Canada/Yukon'',
486 => ''CET'',
487 => ''Chile/Continental'',
488 => ''Chile/EasterIsland'',
489 => ''CST6CDT'',
490 => ''Cuba'',
491 => ''EET'',
492 => ''Egypt'',
493 => ''Eire'',
494 => ''EST'',
495 => ''EST5EDT'',
496 => ''Etc/GMT'',
497 => ''Etc/GMT+0'',
498 => ''Etc/GMT+1'',
499 => ''Etc/GMT+10'',
500 => ''Etc/GMT+11'',
501 => ''Etc/GMT+12'',
502 => ''Etc/GMT+2'',
503 => ''Etc/GMT+3'',
504 => ''Etc/GMT+4'',
505 => ''Etc/GMT+5'',
506 => ''Etc/GMT+6'',
507 => ''Etc/GMT+7'',
508 => ''Etc/GMT+8'',
509 => ''Etc/GMT+9'',
510 => ''Etc/GMT-0'',
511 => ''Etc/GMT-1'',
512 => ''Etc/GMT-10'',
513 => ''Etc/GMT-11'',
514 => ''Etc/GMT-12'',
515 => ''Etc/GMT-13'',
516 => ''Etc/GMT-14'',
517 => ''Etc/GMT-2'',
518 => ''Etc/GMT-3'',
519 => ''Etc/GMT-4'',
520 => ''Etc/GMT-5'',
521 => ''Etc/GMT-6'',
522 => ''Etc/GMT-7'',
523 => ''Etc/GMT-8'',
524 => ''Etc/GMT-9'',
525 => ''Etc/GMT0'',
526 => ''Etc/Greenwich'',
527 => ''Etc/UCT'',
528 => ''Etc/Universal'',
529 => ''Etc/UTC'',
530 => ''Etc/Zulu'',
531 => ''Factory'',
532 => ''GB'',
533 => ''GB-Eire'',
534 => ''GMT'',
535 => ''GMT+0'',
536 => ''GMT-0'',
537 => ''GMT0'',
538 => ''Greenwich'',
539 => ''Hongkong'',
540 => ''HST'',
541 => ''Iceland'',
542 => ''Iran'',
543 => ''Israel'',
544 => ''Jamaica'',
545 => ''Japan'',
546 => ''Kwajalein'',
547 => ''Libya'',
548 => ''MET'',
549 => ''Mexico/BajaNorte'',
550 => ''Mexico/BajaSur'',
551 => ''Mexico/General'',
552 => ''MST'',
553 => ''MST7MDT'',
554 => ''Navajo'',
555 => ''NZ'',
556 => ''NZ-CHAT'',
557 => ''Poland'',
558 => ''Portugal'',
559 => ''PRC'',
560 => ''PST8PDT'',
561 => ''ROC'',
562 => ''ROK'',
563 => ''Singapore'',
564 => ''Turkey'',
565 => ''UCT'',
566 => ''Universal'',
567 => ''US/Alaska'',
568 => ''US/Aleutian'',
569 => ''US/Arizona'',
570 => ''US/Central'',
571 => ''US/East-Indiana'',
572 => ''US/Eastern'',
573 => ''US/Hawaii'',
574 => ''US/Indiana-Starke'',
575 => ''US/Michigan'',
576 => ''US/Mountain'',
577 => ''US/Pacific'',
578 => ''US/Pacific-New'',
579 => ''US/Samoa'',
580 => ''UTC'',
581 => ''W-SU'',
582 => ''WET'',
583 => ''Zulu'',
)

Answer 2

¿''UTC'' es un identificador de zona horaria válido en su sistema?

<?php
if (date_default_timezone_set(''UTC'')){
echo "UTC is a valid time zone";
}else{
echo "The system doesn''t know WTFUTC. Maybe try updating tzinfo with your package manager?";
}

Answer 3

El problema es que está mostrando time() , que es una marca de tiempo UNIX basada en GMT / UTC. Es por eso que no cambia. date() por otro lado, formatea la hora según esa marca de tiempo.

Una marca de tiempo es la cantidad de segundos desde la Época Unix (1 de enero de 1970 a las 00:00:00 GMT).

echo date(''Y-m-d H:i:s T'', time()) . "<br>/n";
date_default_timezone_set(''UTC'');
echo date(''Y-m-d H:i:s T'', time()) . "<br>/n";

Answer 4

UTC es definitivamente una zona horaria válida. Es simplemente una abreviación de Tiempo Universal Coordinado. Además, recuerde que date_default_timezone_set acepta uno de los siguientes valores:

 $timezones=array(
"America/Adak",
"America/Argentina/Buenos_Aires",
"America/Argentina/La_Rioja",
"America/Argentina/San_Luis",
"America/Atikokan",
"America/Belem",
"America/Boise",
"America/Caracas",
"America/Chihuahua",
"America/Cuiaba",
"America/Denver",
"America/El_Salvador",
"America/Godthab",
"America/Guatemala",
"America/Hermosillo",
"America/Indiana/Tell_City",
"America/Inuvik",
"America/Kentucky/Louisville",
"America/Lima",
"America/Managua",
"America/Mazatlan",
"America/Mexico_City",
"America/Montreal",
"America/Nome",
"America/Ojinaga",
"America/Port-au-Prince",
"America/Rainy_River",
"America/Rio_Branco",
"America/Santo_Domingo",
"America/St_Barthelemy",
"America/St_Vincent",
"America/Tijuana",
"America/Whitehorse",
"America/Anchorage",
"America/Argentina/Catamarca",
"America/Argentina/Mendoza",
"America/Argentina/Tucuman",
"America/Atka",
"America/Belize",
"America/Buenos_Aires",
"America/Catamarca",
"America/Coral_Harbour",
"America/Curacao",
"America/Detroit",
"America/Ensenada",
"America/Goose_Bay",
"America/Guayaquil",
"America/Indiana/Indianapolis",
"America/Indiana/Vevay",
"America/Iqaluit",
"America/Kentucky/Monticello",
"America/Los_Angeles",
"America/Manaus",
"America/Mendoza",
"America/Miquelon",
"America/Montserrat",
"America/Noronha",
"America/Panama",
"America/Port_of_Spain",
"America/Rankin_Inlet",
"America/Rosario",
"America/Sao_Paulo",
"America/St_Johns",
"America/Swift_Current",
"America/Toronto",
"America/Winnipeg",
"America/Anguilla",
"America/Argentina/ComodRivadavia",
"America/Argentina/Rio_Gallegos",
"America/Argentina/Ushuaia",
"America/Bahia",
"America/Blanc-Sablon",
"America/Cambridge_Bay",
"America/Cayenne",
"America/Cordoba",
"America/Danmarkshavn",
"America/Dominica",
"America/Fort_Wayne",
"America/Grand_Turk",
"America/Guyana",
"America/Indiana/Knox",
"America/Indiana/Vincennes",
"America/Jamaica",
"America/Knox_IN",
"America/Louisville",
"America/Marigot",
"America/Menominee",
"America/Moncton",
"America/Nassau",
"America/North_Dakota/Beulah",
"America/Pangnirtung",
"America/Porto_Acre",
"America/Recife",
"America/Santa_Isabel",
"America/Scoresbysund",
"America/St_Kitts",
"America/Tegucigalpa",
"America/Tortola",
"America/Yakutat",
"America/Antigua",
"America/Argentina/Cordoba",
"America/Argentina/Salta",
"America/Aruba",
"America/Bahia_Banderas",
"America/Boa_Vista",
"America/Campo_Grande",
"America/Cayman",
"America/Costa_Rica",
"America/Dawson",
"America/Edmonton",
"America/Fortaleza",
"America/Grenada",
"America/Halifax",
"America/Indiana/Marengo",
"America/Indiana/Winamac",
"America/Jujuy",
"America/Kralendijk",
"America/Lower_Princes",
"America/Martinique",
"America/Merida",
"America/Monterrey",
"America/New_York",
"America/North_Dakota/Center",
"America/Paramaribo",
"America/Porto_Velho",
"America/Regina",
"America/Santarem",
"America/Shiprock",
"America/St_Lucia",
"America/Thule",
"America/Vancouver",
"America/Yellowknife",
"America/Araguaina",
"America/Argentina/Jujuy",
"America/Argentina/San_Juan",
"America/Asuncion",
"America/Barbados",
"America/Bogota",
"America/Cancun",
"America/Chicago",
"America/Creston",
"America/Dawson_Creek",
"America/Eirunepe",
"America/Glace_Bay",
"America/Guadeloupe",
"America/Havana",
"America/Indiana/Petersburg",
"America/Indianapolis",
"America/Juneau",
"America/La_Paz",
"America/Maceio",
"America/Matamoros",
"America/Metlakatla",
"America/Montevideo",
"America/Nipigon",
"America/North_Dakota/New_Salem",
"America/Phoenix",
"America/Puerto_Rico",
"America/Resolute",
"America/Santiago",
"America/Sitka",
"America/St_Thomas",
"America/Thunder_Bay",
"America/Virgin",
"Indian/Antananarivo",
"Indian/Kerguelen",
"Indian/Reunion",
"Australia/ACT",
"Australia/Currie",
"Australia/Lindeman",
"Australia/Perth",
"Australia/Victoria",
"Europe/Amsterdam",
"Europe/Berlin",
"Europe/Chisinau",
"Europe/Helsinki",
"Europe/Kiev",
"Europe/Madrid",
"Europe/Moscow",
"Europe/Prague",
"Europe/Sarajevo",
"Europe/Tallinn",
"Europe/Vatican",
"Europe/Zagreb",
"Pacific/Apia",
"Pacific/Efate",
"Pacific/Galapagos",
"Pacific/Johnston",
"Pacific/Marquesas",
"Pacific/Noumea",
"Pacific/Ponape",
"Pacific/Tahiti",
"Pacific/Wallis",
"Indian/Chagos",
"Indian/Mahe",
"Australia/Adelaide",
"Australia/Darwin",
"Australia/Lord_Howe",
"Australia/Queensland",
"Australia/West",
"Europe/Andorra",
"Europe/Bratislava",
"Europe/Copenhagen",
"Europe/Isle_of_Man",
"Europe/Lisbon",
"Europe/Malta",
"Europe/Nicosia",
"Europe/Riga",
"Europe/Simferopol",
"Europe/Tirane",
"Europe/Vienna",
"Europe/Zaporozhye",
"Pacific/Auckland",
"Pacific/Enderbury",
"Pacific/Gambier",
"Pacific/Kiritimati",
"Pacific/Midway",
"Pacific/Pago_Pago",
"Pacific/Port_Moresby",
"Pacific/Tarawa",
"Pacific/Yap",
"Africa/Abidjan",
"Africa/Asmera",
"Africa/Blantyre",
"Africa/Ceuta",
"Africa/Douala",
"Africa/Johannesburg",
"Africa/Kinshasa",
"Africa/Lubumbashi",
"Africa/Mbabane",
"Africa/Niamey",
"Africa/Timbuktu",
"Africa/Accra",
"Africa/Bamako",
"Africa/Brazzaville",
"Africa/Conakry",
"Africa/El_Aaiun",
"Africa/Juba",
"Africa/Lagos",
"Africa/Lusaka",
"Africa/Mogadishu",
"Africa/Nouakchott",
"Africa/Tripoli",
"Africa/Addis_Ababa",
"Africa/Bangui",
"Africa/Bujumbura",
"Africa/Dakar",
"Africa/Freetown",
"Africa/Kampala",
"Africa/Libreville",
"Africa/Malabo",
"Africa/Monrovia",
"Africa/Ouagadougou",
"Africa/Tunis",
"Africa/Algiers",
"Africa/Banjul",
"Africa/Cairo",
"Africa/Dar_es_Salaam",
"Africa/Gaborone",
"Africa/Khartoum",
"Africa/Lome",
"Africa/Maputo",
"Africa/Nairobi",
"Africa/Porto-Novo",
"Africa/Windhoek",
"Africa/Asmara",
"Africa/Bissau",
"Africa/Casablanca",
"Africa/Djibouti",
"Africa/Harare",
"Africa/Kigali",
"Africa/Luanda",
"Africa/Maseru",
"Africa/Ndjamena",
"Africa/Sao_Tome",
"Atlantic/Azores",
"Atlantic/Faroe",
"Atlantic/St_Helena",
"Atlantic/Bermuda",
"Atlantic/Jan_Mayen",
"Atlantic/Stanley",
"Atlantic/Canary",
"Atlantic/Madeira",
"Atlantic/Cape_Verde",
"Atlantic/Reykjavik",
"Atlantic/Faeroe",
"Atlantic/South_Georgia",
"Asia/Aden",
"Asia/Aqtobe",
"Asia/Baku",
"Asia/Calcutta",
"Asia/Dacca",
"Asia/Dushanbe",
"Asia/Hong_Kong",
"Asia/Jayapura",
"Asia/Kashgar",
"Asia/Kuala_Lumpur",
"Asia/Magadan",
"Asia/Novokuznetsk",
"Asia/Pontianak",
"Asia/Riyadh",
"Asia/Shanghai",
"Asia/Tehran",
"Asia/Ujung_Pandang",
"Asia/Vladivostok",
"Asia/Almaty",
"Asia/Ashgabat",
"Asia/Bangkok",
"Asia/Choibalsan",
"Asia/Damascus",
"Asia/Gaza",
"Asia/Hovd",
"Asia/Jerusalem",
"Asia/Kathmandu",
"Asia/Kuching",
"Asia/Makassar",
"Asia/Novosibirsk",
"Asia/Pyongyang",
"Asia/Saigon",
"Asia/Singapore",
"Asia/Tel_Aviv",
"Asia/Ulaanbaatar",
"Asia/Yakutsk",
"Asia/Amman",
"Asia/Ashkhabad",
"Asia/Beirut",
"Asia/Chongqing",
"Asia/Dhaka",
"Asia/Harbin",
"Asia/Irkutsk",
"Asia/Kabul",
"Asia/Katmandu",
"Asia/Kuwait",
"Asia/Manila",
"Asia/Omsk",
"Asia/Qatar",
"Asia/Sakhalin",
"Asia/Taipei",
"Asia/Thimbu",
"Asia/Ulan_Bator",
"Asia/Yekaterinburg",
"Asia/Anadyr",
"Asia/Baghdad",
"Asia/Bishkek",
"Asia/Chungking",
"Asia/Dili",
"Asia/Hebron",
"Asia/Istanbul",
"Asia/Kamchatka",
"Asia/Kolkata",
"Asia/Macao",
"Asia/Muscat",
"Asia/Oral",
"Asia/Qyzylorda",
"Asia/Samarkand",
"Asia/Tashkent",
"Asia/Thimphu",
"Asia/Urumqi",
"Asia/Yerevan",
"Asia/Aqtau",
"Asia/Bahrain",
"Asia/Brunei",
"Asia/Colombo",
"Asia/Dubai",
"Asia/Ho_Chi_Minh",
"Asia/Jakarta",
"Asia/Karachi",
"Asia/Krasnoyarsk",
"Asia/Macau",
"Asia/Nicosia",
"Asia/Phnom_Penh",
"Asia/Rangoon",
"Asia/Seoul",
"Asia/Tbilisi",
"Asia/Tokyo",
"Asia/Vientiane",
"Australia/Canberra",
"Australia/LHI",
"Australia/NSW",
"Australia/Tasmania",
"Australia/Broken_Hill",
"Australia/Hobart",
"Australia/North",
"Australia/Sydney",
"Pacific/Chuuk",
"Pacific/Fiji",
"Pacific/Guam",
"Pacific/Kwajalein",
"Pacific/Niue",
"Pacific/Pitcairn",
"Pacific/Saipan",
"Pacific/Truk",
"Pacific/Chatham",
"Pacific/Fakaofo",
"Pacific/Guadalcanal",
"Pacific/Kosrae",
"Pacific/Nauru",
"Pacific/Palau",
"Pacific/Rarotonga",
"Pacific/Tongatapu",
"Pacific/Easter",
"Pacific/Funafuti",
"Pacific/Honolulu",
"Pacific/Majuro",
"Pacific/Norfolk",
"Pacific/Pohnpei",
"Pacific/Samoa",
"Pacific/Wake",
"Antarctica/Casey",
"Antarctica/McMurdo",
"Antarctica/Vostok",
"Antarctica/Davis",
"Antarctica/Palmer",
"Antarctica/DumontDUrville",
"Antarctica/Rothera",
"Antarctica/Macquarie",
"Antarctica/South_Pole",
"Antarctica/Mawson",
"Antarctica/Syowa",
"Arctic/Longyearbyen",
"Europe/Athens",
"Europe/Brussels",
"Europe/Dublin",
"Europe/Istanbul",
"Europe/Ljubljana",
"Europe/Mariehamn",
"Europe/Oslo",
"Europe/Rome",
"Europe/Skopje",
"Europe/Tiraspol",
"Europe/Vilnius",
"Europe/Zurich",
"Europe/Belfast",
"Europe/Bucharest",
"Europe/Gibraltar",
"Europe/Jersey",
"Europe/London",
"Europe/Minsk",
"Europe/Paris",
"Europe/Samara",
"Europe/Sofia",
"Europe/Uzhgorod",
"Europe/Volgograd",
"Europe/Belgrade",
"Europe/Budapest",
"Europe/Guernsey",
"Europe/Kaliningrad",
"Europe/Luxembourg",
"Europe/Monaco",
"Europe/Podgorica",
"Europe/San_Marino",
"Europe/Stockholm",
"Europe/Vaduz",
"Europe/Warsaw",
"Indian/Cocos",
"Indian/Mauritius",
"Indian/Christmas",
"Indian/Maldives",
"Indian/Comoro",
"Indian/Mayotte",
"Australia/Brisbane",
"Australia/Eucla",
"Australia/Melbourne",
"Australia/South",
"Australia/Yancowinna",
);

Zonas horarias en PHP en http://www.php.net/manual/en/timezones.php