Monthly values

Figure 3 shows the monthly mean and minimum value (the absolute lowest value in all of the data for that month) for all of the data. Again, the seasonal variation is clearly evident. The wet summer months have a mean precipitable water which is more than twice what it is in the winter months. The typical mean precipitable water in the ``winter'' months (November - April) is about 5 mm, while in the middle of ``monsoon'' season (July and August), the typical mean precipitable water is as bad as almost 15 mm. The absolute very best conditions are about 1 mm of precipitable water in the months from December to April, about 2 mm in October, November, May, and June, about 3 mm in July and September, and about 6 mm in August.

Figure 3: Monthly mean (open stars) and absolute minimum (filled stars) values of precipitable water.