Abstract
A severe damage from the late frost mainly on fruit trees and mulberry, broke out over the southern district of Northeast Japan, on 29 April, 1964. The difference of the minimum air temperature from the long term average temperature shows an uneven distribution with its maximum in the southern parts of Miyagi prefecture and central parts of Fukushima prefecture (Fig. 1) . We surveyed the Igu Basin (Miyagi pref.), which is one of the core regions suffered from the damage and was distinguished from slightly damaged regions (coastal plain) by the hills 200-300 m. high. According to the field map showing the degrees of damage on mulberry leaves (Fig. 3), there are some warm islands of slightly damaged areas at the opening of the Abukuma Valley into the basin, and also there is an area where the distribution is complicated in the northern basin adjacent to the coastal plain. Such a distribution of the damage as Fig. 3 will present the key to solve the climatic nature of small basins.
