The purpose of this study is to investigate the occurrence of land and sea breezes in Tohoku district on calm days during warm period.　The investigated period covers from May to October of 1993-1995.
As a result of the investigation, it is cleared that the sea breeze occurred and developed at every coastal plain on calm days during warm period with weak synoptic wind.　In these cases, the low pressure area (heat low) was developed in the inland.
At the same time, it is suggested that whether the sea breeze is appeared in Kitakami lower land is closely related to the direction of synoptic upper layer wind and atmospheric stability.　Also it is cleared that when the local pressure field have zonal asymmetry or no-uniformity, the patter of the occurrence of the sea breeze is also changed.
The diurnal variation of the wind fields of the case that the sea breezes occur at every plain is also investigated.　It is revealed that the duration of the sea breeze blowing is very different between the Japan Sea side and Pacific side.　This difference is mainly related to the local pressure fields that the east area becomes higher pressure and the west becomes lower in the night time.　Consequently, it is suggested that such local pressure fields are affected by the synoptic pressure gradient.

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