3 delays so far, all due to technical issues. First 2 were issues around the orbital maneuvering system. The latest is due to an electrical problem in the main engines. Current schedule has launch moved to Thursday Nov 4 at 3:29 pm EDT. That’s looking a bit optismitic with the forecast showing rain, wind, and low clouds. Forecast as of this morning has only a 30% of favorable conditions for launch. Details on the criteria NASA uses in determine if the weather is good enough to allow for launch see the Space Shuttle Weather Launch Commit Criteria, which has been updated over the years but most influenced by the loss of Challenger during STS-51L in unusually cold weather.
The forecast issued by the Air Force used by NASA in planning is available here . It is updated each morning around 7:15 am starting 5 days ahead of the first scheduled launch.