雨影或雨影区是指沉降幅度较小的地区，如山脉背风坡的干燥区域。例如，中加州东部的白山脉位处内华达山脉的雨影中。而形成雨影的地理现象叫雨影效应。

海洋的暖湿气流被地形阻挡，迎风坡形成地形雨；背风坡因水分减少，气流下降时气温升高，相对湿度降低，因而云雨少见，降水量明显减少，背风面形成雨影。

A rain shadow is a dry area on the leeward side of a mountainous area (away from the wind). The mountains block the passage of rain-producing weather systems and cast a "shadow" of dryness behind them.

As shown by the diagram, the incoming warm and moist air is drawn by the prevailing winds towards the top of the mountains, where it condenses and precipitates before it crosses the top. The air, without much moisture left, advances behind the mountains creating a drier side called the "rain shadow".