What you have described is a common problem and is a natural reaction. When the sun is shining the brightness and glare interfere with comfortable vision
and the ability to see clearly by causing squinting and eye
watering. This is caused by the UV rays in the sunlight. This is why people are advised to wear sunglasses to protect their eyes in the bright sun.
When choosing sunglasses make sure you pick a good brand as your eyes can be affected by substandard lens that many cheaper sunglasses use.