Quote from dbphoenix:
We tend to equate "opening" with the NY open, as though NY is the only market in the world. However, the volume as a rule occurs during the NY session.
The opening low, then, tends to be of greater significance because a greater number of traders created it. This is not to say that the premarket low should be ignored. Rather it should be considered among a number of factors, such as whether price swung wildly premarket or settled into a steady, tight range. What, in other words, might traders have in mind?