This paper presents a methodology to determine the days and times of the year when sun glare may impair drivers’ vision on a particular road section, depending on the geographic location, the geometric design of the road, and the physical characteristics of the environment. The methodology is based on applying cylindrical charts to represent the entire set of variables involved in the problem. The results may be used to study in detail the problem at critical sections of existing or newly designed roads such as intersections, freeway ramps, and tunnel exits. The methodology may also support the use of variable message signs to warn drivers of the risk of vision impairment at the exact times and locations where high-glare conditions occur.