They don't expose your address, just your city. And I do use your weather station, but the weather station you picked isn't very good. For example, for Sept.15 this is all it has:
http://www.wunderground.com/history/station/94763/2009/09/15/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA&format=l
12:00 AM,58,54,84,,,WSW,4.6,,,,
3:00 AM,58,54,83,,,South,3.5,,,,
6:00 AM,58,55,85,,,East,2.3,,,,
12:00 PM,72,53,41,,,North,12.7,,,,
3:00 PM,77,53,32,,,ENE,5.8,,,,
6:00 PM,68,58,63,,,North,5.8,,,,
9:00 PM,60,59,94,,,NE,1.2,,,,
So, it only samples every 3 hours and there are no weather conditions which I think may actually be the problem and not the timezone. Compare that to a weather station like YSRI where you get:
http://www.wunderground.com/history/airport/YSRI/2009/09/15/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA&format=l
12:00 AM,59.0,53.6,82,30.18,6.2,SW,3.5,-,N/A,,Overcast
12:30 AM,59.0,53.6,82,30.18,6.2,SW,5.8,-,N/A,,Overcast
1:00 AM,59.0,53.6,82,30.18,6.2,SW,5.8,-,N/A,,Overcast
1:30 AM,59.0,53.6,82,30.15,5.6,SW,3.5,-,N/A,,Overcast
2:00 AM,57.2,53.6,88,30.15,5.6,SSW,3.5,-,N/A,,Overcast
2:30 AM,57.2,53.6,88,30.12,5.6,Calm,Calm,-,N/A,,Overcast
3:00 AM,57.2,53.6,88,30.12,5.6,Calm,Calm,-,N/A,,Overcast
3:30 AM,57.2,53.6,88,30.12,5.6,Calm,Calm,-,N/A,,Overcast
5:00 AM,57.2,53.6,88,30.12,5.6,Calm,Calm,-,N/A,,Overcast
5:30 AM,57.2,53.6,88,30.12,5.6,Calm,Calm,-,N/A,,Overcast
6:00 AM,57.2,53.6,88,30.15,5.6,Calm,Calm,-,N/A,,Overcast
6:30 AM,57.2,53.6,88,30.15,5.6,Calm,Calm,-,N/A,,Overcast
7:00 AM,59.0,53.6,82,30.15,5.6,Calm,Calm,-,N/A,,Overcast
7:30 AM,59.0,53.6,82,30.15,5.6,Calm,Calm,-,N/A,,Overcast
8:00 AM,59.0,53.6,82,30.15,5.6,Calm,Calm,-,N/A,,Overcast
8:30 AM,60.8,53.6,77,30.15,5.6,Calm,Calm,-,N/A,,Overcast
9:00 AM,60.8,53.6,77,30.15,6.2,NE,2.3,-,N/A,,Overcast
9:30 AM,62.6,55.4,77,30.15,5.6,Calm,Calm,-,N/A,,Overcast
10:00 AM,64.4,55.4,73,30.12,5.6,East,1.2,-,N/A,,Overcast
10:30 AM,68.0,55.4,64,30.12,6.2,NE,2.3,-,N/A,,Mostly Cloudy
11:00 AM,68.0,57.2,68,30.09,6.2,ENE,5.8,-,N/A,,Overcast
11:30 AM,69.8,57.2,64,30.06,6.2,NE,6.9,-,N/A,,Scattered Clouds
12:00 PM,69.8,55.4,60,30.06,6.2,NNE,9.2,-,N/A,,Unknown
12:30 PM,71.6,55.4,57,30.04,6.2,NNE,8.1,-,N/A,,Unknown
1:00 PM,71.6,57.2,60,30.01,6.2,ENE,5.8,-,N/A,,Unknown
1:30 PM,73.4,57.2,57,30.01,6.2,ENE,6.9,-,N/A,,Unknown
2:00 PM,73.4,55.4,53,29.98,6.2,ENE,5.8,-,N/A,,Unknown
2:30 PM,75.2,55.4,50,29.98,6.2,East,8.1,-,N/A,,Unknown
3:00 PM,75.2,55.4,50,29.98,6.2,East,8.1,-,N/A,,Unknown
3:30 PM,75.2,55.4,50,29.98,6.2,East,6.9,-,N/A,,Unknown
4:00 PM,75.2,55.4,50,29.98,6.2,East,8.1,-,N/A,,Unknown
4:30 PM,73.4,57.2,57,29.98,6.2,East,11.5,-,N/A,,Unknown
5:00 PM,69.8,57.2,64,29.98,6.2,East,10.4,-,N/A,,Unknown
5:30 PM,68.0,57.2,68,30.01,6.2,East,9.2,-,N/A,,Unknown
6:00 PM,66.2,57.2,73,30.01,6.2,East,6.9,-,N/A,,Unknown
6:30 PM,64.4,57.2,77,30.04,6.2,East,5.8,-,N/A,,Unknown
7:00 PM,62.6,57.2,82,30.04,6.2,SSE,1.2,-,N/A,,Unknown
7:30 PM,60.8,55.4,82,30.06,6.2,South,3.5,-,N/A,,Unknown
8:00 PM,60.8,55.4,82,30.06,6.2,South,2.3,-,N/A,,Unknown
8:30 PM,60.8,57.2,88,30.06,6.2,SE,4.6,-,N/A,,Unknown
9:00 PM,60.8,57.2,88,30.09,6.2,ESE,5.8,-,N/A,,Unknown
9:30 PM,57.2,53.6,88,30.09,5.6,Calm,Calm,-,N/A,,Unknown
10:00 PM,57.2,55.4,94,30.09,5.6,Calm,Calm,-,N/A,,Unknown
10:21 PM,55.4,55.4,100,30.09,3.7,Calm,Calm,-,N/A,,Unknown
10:30 PM,55.4,53.6,94,30.09,3.7,Calm,Calm,-,N/A,,Unknown
11:00 PM,55.4,53.6,94,30.09,4.3,Calm,Calm,-,N/A,,Unknown
11:03 PM,55.4,53.6,94,30.09,4.3,Calm,Calm,-,N/A,,Unknown
11:30 PM,53.6,51.8,94,30.12,6.2,WSW,1.2,-,N/A,,Unknown
The Unknowns there isn't great, so that one could be better too, but it is way better than the one you picked. Generally the 4-letter ones are airport-based and much more accurate than the all-numeric ones.
If you look at the weather station map there are plenty of others nearby:
http://www.wunderground.com/wundermap/?lat=-33.72000122&lon=150.66999817&zoom=10