I'm actually using the 4s ! ( I don't usually buy new phones until my old one breaks )
And it's pretty damn accurate on this so ,on newer phones, it might work better I'm not sure.
It's hammering down in Lancashire but had about an hour when it stopped, ( it actually says' rain in 12 minutes ) so it helped me plan for that, instead of getting ready for a full day, I just did an hour, then the rain started and I couldn't see looking up lol . It's saying dry tomorrow, so will hopefully catch up abit tomorrow .