Before the declaration, JMA officials walked around the sample tree, surrounded by a wooden fence, to confirm that at least 80 per cent of the tree's flowers had opened, the benchmark for "full bloom." The cherry blossoms are expected to peak for a week to ten days. The tree started blooming on 29 March, the latest date in the last ten years. However, it only took six days for the flowers to reach peak bloom, one day shorter than the average in the past. "Temperatures were low in February and March when flower buds were growing, but unseasonably high temperatures over the last weekend pushed the opening flowers to full blossom," the JMA said of the timing. The cherry tree at the shrine has been used as Tokyo's benchmark tree since 1966. It is one of 58 designated sample trees across Japan. Tokyo's tree was the 13th to be declared in full bloom.