Wide-area monitoring system (WAMS) is emerging technologies that utilize phasor measurement units (PMUs) combined with highly accurate time synchronization to deliver the time-synchronized phasor data known as “synchrophasor”. To enable more extensive applications from WAMS, an excellent synchrophasor data availability level is a must-have. In this paper, a developed software application tool for analyzing data availability and classifying causes of unavailable data is presented. The developed software tool demonstration has been done by using the actual synchrophasor data retrieved from WAMS currently installed for Thailand power grid. The synchrophasor data analysis results based on one-month and daily availability statistics are shown using visualization charts. The results indicate that the current data availability from WAMS, on average, may not yet reach the excellent level that is adequately suitable for real-time control and protection applications. The data analysis results obtained from the developed software tool can provide insightful information to guide what the data problems might be, so that appropriate corrective actions can be implemented to improve the data availability.