Usually, people's eyes will watery when they get allergies and infection etc. Besides, When you feel pain, exciting and moved, you will react with tears. Still if you sensitive to light, you may get watery eyes when you walk outsides in sunny days. Just you'd better check your eyes first so as to know why do your eyes water when you walk outside.
Because when the air temperature drops or you face the wind, our eyes will be stimulated and they start to come out water. So when you walk outside in cold days, it means you face the wind and the cold weather, so your eyes react. To avoid this happening, you can use some eyedrops.
Well, generally speaking, it is very normal to have this symptom. For the reason, I have to tell you that the light is so strong that when we open our eyes to see it, it will just make the eyes be hurt. And also our eyes are so very sensitive that they will react to the stimulation from sun light. When the sunlight gets into our eyes, it will make our eyes to adjust to it. And at this time, it will water. So it is very normal. And also, there are many dirty objects in the air outside, so when you go out, your eyes are easy to be infected by them. In this situation, maybe you should go and see a doctor so that you can talk about your problems, then can have the eye exam. You should not make your eyes to be exposed under the sunlight for a long time, also should be careful about the dirty things outside.