Raw data (and I mean really raw) is the lifeblood of meteorology. Fortunately, there is a fair amount of it available on the net if you know where to dig. I have listed the main sources of global raw data here. True raw data is transmitted in codes that are internationally agreed through the World Meteorological Organisation. These codes and details of the bulletins in which they are transmitted fill many volumes, but the data is so useful that it is worth your while, if you are really enthusiastic, learning to deal with the codes using the sites below. In the meantime, if you don't know your TTAAs from your SYNOPs, you can always download Tim Vasquez's excellent Digital Atmosphere program, which takes this raw data and plots it onto maps you can customise yourself. It also produces upper air diagrams and maps.. (21/03/00)

The following are useful resources when dealing with raw data:

1. Weather Communication Codes. Author Hugh Stegman describes this as a "Breathless Overview", but it gives a good introduction to why codes are essential in reporting and exchanging weather data at a professional level as well as the information you need for a modest understanding of them. It is written from a US perspective, but most is applicable globally. I have reformatted it with section links to make it easier to find what you want.
2. Manual on Codes -- Volume I.1 Part A: Alphanumeric codes, Volume I.2 Part B: Binary codes and Part C: Common features to binary and alpha-numeric codes, and Volume II - Regional codes and national coding practices by World Meteorological Organisation. This is the bible for anyone wanting to decode standard alpha-numeric weather codes such as the SYNOP, METAR, upper air and drifting buoy weather message codes that are used for international exchange of raw data. Volume 1 covers global standards, Volume 2 regional standards (Australia is in Region V. (01/07/07)
3. Weathergraph observation, plotting and forecasting summary chart from Tim Vasquez at Weathergraphics. This enormously useful chart is in pdf format and prints out onto two A4 pages. While it is oriented towards US and northern hemisphere circumstances, it is still a powerful reference for Australian users. It contains concise summaries of the main surface weather codes and the symbols used in plotting synoptic charts, summaries of standard hailstone sizes, the Fujita tornado scale, beaufort wind scale, meteorological conversion units, the Saffir-Simpson Hurricane Scale, weather system categories, stability indices, computer forecast models, and a range of forecasting rules-of-thumb which need some adjustment for use in Australia. (28/12/02)
4. Details of meteorological SYNOP, METAR, TEMP and CLIMAT codes from Unisys (13/04/00)
5. Details of meteorological SYNOP code from Dave Wheeler (21/03/00)
6. Details of meteorological SYNOP code from UK Weather Information Site (13/04/00)
7. How to decode upper air data and Skew T diagrams from UCSD (21/03/00)
8. Complete and up-to-date lists of Australian synoptic and rainfall stations are available here, and there's a wealth of metadata about Australian weather records if you explore the subdirectories here. (09/06/01)
9. Australian Aviation Weather Users Guide from the BoM explains METARs, TAFs and other aviation-related weather services. (21/03/00)
10. My own rough and ready Guide to Australian METARs and some of the location codes they use (21/03/00)
11. A comprehensive page on weather station WMO and ICAO identifiers, and list of links to relevant databases on the Web, and relevant software; from WeatherGraphics. (17/03/01)
12. WMO Distributed Databases, including online copies of Publication 9 Volume A (all the world's weather stations), Volume C (the contents of WMO weather bulletins), and Publication 47 (a list of ships reporting the weather). (21/03/00)
13. Global weather station names, WMO numbers, ICAO codes, locations and elevations is available from the US NWS here (21/03/00)
14. Global weather station finder: key in the ICAO 4-letter code or the WMO 5-digit code to find the station details, or key in the station to get the code. From Digital Atmosphere (13/04/00)
15. Another weather station finder from Unidata: key in ICAO code, WMO code or station name to find brief station details. (24/09/00)
16. US NWS Met Codes Page has information on changes to codes. (21/03/00)
17. Searchable US NWS database can be used to find updates on codes, headers, etc. Try entering wmo codes. (21/03/00)
18. A great amount of information on the Global Telecommunications System (GTS) from UK Weather Information Site (13/04/00)