Well... Rain on it's own is just water, and though it can dry hair a bit with repetition it is generally fine for your hair. Sadly, with all the pollution in the air, especially in larger cities and areas with factories near-by, clouds and falling rain can become polluted and leave chemicals, dirt and pollutive residue in your hair, which can be bad for it.
no, probably not. dirt and pollution gather in the clouds and when it rains the dirt goes along with the water, and falling unto our heads.
my mom sometimes washes her hair in rain water..lol..and i tried it once..it makes it very very soft..lol..
yes, rain is very good for your hair.