I agree that it depends on the country you live in. In my country it's nor very common to talk to strangers, but still some poeple do that, so it depends on your character as well. 

I think you dont' have to do that if it makes you feel uncomfortable, but if you still want to try, you should check first if it's a right place and right person to start, and then make some comments about the weather/situation and see what's happening)