dateutil‘s parser.parse() accepts as keyword argument tzinfos a dictionary of the kind {'EST': -5*3600} (that is, matching the zone name to GMT offset in seconds). So assuming we have that, we can do:
>>> import dateutil.parser as dp
>>> s="Sat, 11/01/09 8:00PM"
>>> for tz_code in ('PST','PDT','MST','MDT','CST','CDT','EST','EDT'):
>>> dt = s+' '+tz_code
>>> print dt, '=', dp.parse(dt, tzinfos=tzd)
Sat, 11/01/09 8:00PM PST = 2009-11-01 20:00:00-08:00
Sat, 11/01/09 8:00PM PDT = 2009-11-01 20:00:00-07:00
Sat, 11/01/09 8:00PM MST = 2009-11-01 20:00:00-07:00
Sat, 11/01/09 8:00PM MDT = 2009-11-01 20:00:00-06:00
Sat, 11/01/09 8:00PM CST = 2009-11-01 20:00:00-06:00
Sat, 11/01/09 8:00PM CDT = 2009-11-01 20:00:00-05:00
Sat, 11/01/09 8:00PM EST = 2009-11-01 20:00:00-05:00
Sat, 11/01/09 8:00PM EDT = 2009-11-01 20:00:00-04:00
Regarding the content of tzinfos, here is how i populated mine:
tz_str=""'-12 Y
-11 X NUT SST
-10 W CKT HAST HST TAHT TKT
-9 V AKST GAMT GIT HADT HNY
-8 U AKDT CIST HAY HNP PST PT
-7 T HAP HNR MST PDT
-6 S CST EAST GALT HAR HNC MDT
-5 R CDT COT EASST ECT EST ET HAC HNE PET
-4 Q AST BOT CLT COST EDT FKT GYT HAE HNA PYT
-3 P ADT ART BRT CLST FKST GFT HAA PMST PYST SRT UYT WGT
-2 O BRST FNT PMDT UYST WGST
-1 N AZOT CVT EGT
0 Z EGST GMT UTC WET WT
1 A CET DFT WAT WEDT WEST
2 B CAT CEDT CEST EET SAST WAST
3 C EAT EEDT EEST IDT MSK
4 D AMT AZT GET GST KUYT MSD MUT RET SAMT SCT
5 E AMST AQTT AZST HMT MAWT MVT PKT TFT TJT TMT UZT YEKT
6 F ALMT BIOT BTT IOT KGT NOVT OMST YEKST
7 G CXT DAVT HOVT ICT KRAT NOVST OMSST THA WIB
8 H ACT AWST BDT BNT CAST HKT IRKT KRAST MYT PHT SGT ULAT WITA WST
9 I AWDT IRKST JST KST PWT TLT WDT WIT YAKT
10 K AEST ChST PGT VLAT YAKST YAPT
11 L AEDT LHDT MAGT NCT PONT SBT VLAST VUT
12 M ANAST ANAT FJT GILT MAGST MHT NZST PETST PETT TVT WFT
13 FJST NZDT
11.5 NFT
10.5 ACDT LHST
9.5 ACST
6.5 CCT MMT
5.75 NPT
5.5 SLT
4.5 AFT IRDT
3.5 IRST
-2.5 HAT NDT
-3.5 HNT NST NT
-4.5 HLV VET
-9.5 MART MIT'''
tzd = {}
for tz_descr in map(str.split, tz_str.split('\n')):
tz_offset = int(float(tz_descr[0]) * 3600)
for tz_code in tz_descr[1:]:
tzd[tz_code] = tz_offset
ps. per @Hank Gay time zone naming is not clearly defined. To form my table i used http://www.timeanddate.com/library/abbreviations/timezones/ and http://en.wikipedia.org/wiki/List_of_time_zone_abbreviations . I looked at each conflict and resolved conflicts between obscure and popular names towards the popular (more used ones). There was one – IST – that was not as clear cut (it can mean Indian Standard Time, Iran Standard Time, Irish Standard Time or Israel Standard Time), so i left it out of the table – you may need to chose what to add for it based on your location. Oh – and I left out the Republic of Kiribati with their absurd “look at me i am first to celebrate New Year” GMT+13 and GMT+14 time zones.