The North American Monsoon (NAM), which occurs over the southwestern United States and northwestern Mexico, has an immense effect on the climate in this region. Multiple global atmospheric general circulation models (AGCMs) have had difficulty predicting the convective precipitation observed with the NAM, possibly due to the inability of the models to correctly simulate the daily cycle of winds in this region. Hartten et al. (2007) studied the daily cycle of winds over northwestern Mexico during the North American Monsoon Experiment-2004 using winds collected by 915-MHz Doppler wind profilers. This research builds on their work by constructing the mean daily cycle of winds for the lower troposphere at Estaciόn Obispo during the summers of 2005 and 2006. By examining the mean profiles over the entire deployment, as well as the summer-mean daily cycle, we documented the interannual variability in the daily cycle of winds at Estación Obispo. The mean direction profiles showed low-level southwesterlies veering to easterlies in 2004 and 2005, compared to low-level southwesterlies backing to southeasterlies in 2006. The summer mean daily cycle depicted a consistent sea breeze feature over all three years. The summer mean daily cycle also showed southeasterlies at 3000 m in 2004 and 2006, whereas in 2005 easterlies persisted at this height throughout most of the day. The results of this research provide modelers with documentation of the daily cycle of winds, which they can use to verify their models.