How will you know if there is a total Fire Ban on?
If a Total Fire Ban is declared a media release will be issued listing the weather forecast districts involved.
Total Fire Bans will also be announced through newspapers, radio and TV.
If in doubt, ask your local Council, NSW Rural Fire Service, the Police, Fire Brigade or dial 02 9898 1356 (Sydney Metropolitan only).

Links:
Media releases.
Total Fire Ban and Current Fire Danger Map.
NSW Rural Fire service Home Page.

How long does a Fire Ban last? - Usually for 24 hours - from 12 midnight.

Weather Information
Bureau of Meteorology Radar images - http://www.bom.gov.au/weather/radar/
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Rain fall Predictions for Australia:
The forecast from this site has proven very reliable. It shows rain only not cloud, so be aware that if rain is shown near your area it will probably be cloudy in areas nearby. The Images below are a preview of what you will see at the rain fall predictions link above. I have added some locations on the map below as there are none on the official site.

COLA Weather and Climate Data home page - http://www.wxmaps.org/.