Every year from the end of March through the beginning of April, this very popular tourist site becomes even more popular. The Kintai Bridge in Iwakuni is a very famous place to see the cherry blossoms, and every year people flock from all over Japan to see the trees full of blossoms that line the river on either side of the bridge.
Don't be discouraged by bad weather. As you can see from my photos, the blossoms are beautiful even in the rain.
Walking around the Kintai Bridge area is free, but if you would like to cross the bridge there is a small fee for that. There is also plenty of parking near the bridge, but they charge for parking during cherry blossom season so be sure to have some yen for that.
If you take a local train to Iwakuni station, there is a bus that you can catch that will take you to the Kintai Bridge area. There are signs in English so you will know which bus to get on.