As I am learning now that a whole lot depends on the flight school policies.
The instructors will tell you which websites to look for the weather-related information. This will inevitably include METAR and TAF reports that you can get from numerous sources. However, I reckon one school might, for example, only allow lessons if the cloud base were more than 3000 feet (e.g. mine) while others might have no problem with such conditions.
In general it'd be a good idea to learn to interpret METAR/TAF, weather chart, and temperature/wind chart. A lot more becomes clear once you start flying.
@Steve ... I have read your blog. I think you're right that you were lucky with the weather and the flight school. I had nearly 7-8 cancellations due to wx during a 20-day intensive course. This is in Malaga, Spain where I could still go out and enjoy the sun through few/broken ceiling at 2000'
