cold mountain wind; cold Pacific wind in Tōhoku summer
A cool, moist easterly wind that blows from the Pacific Ocean toward the Tōhoku region in summer, often causing crop damage. The term originally referred to a cold wind descending from mountains, but in modern usage it is strongly associated with the regional summer wind.
This year's yamase is especially cold, and we're worried about the rice growth.
山背が吹くと、夏でも気温が上がらない。
When the yamase blows, the temperature doesn't rise even in summer.
Standard kanji spelling for this regional wind term.
Kana spelling is common in everyday writing and weather reports.
The exact derivation is uncertain; the kanji 山 (mountain) and 背 (back) suggest a wind coming from behind the mountains.