热浪是指天气在某一段时间内持续地保持异常高的气温（相对于该地区多年平均气温而言），也有可能伴随有很高的空气湿度。这个术语通常与地区相联系，所以一个处于相对较热气候的地区来说是正常的温度，对另一个通常处于较冷气候的地区来说可能是热浪。

一些地区比较容易受到热浪的袭击，例如欧洲的地中海气候区，澳大利亚的西南和东南沿海地带。除了索马里，赤道没有热浪，因索马里有举世无双的赤道沙漠气候；属于温带沙漠气候的哈萨克斯坦是纬度最高的热浪区。

热浪引起的高温天气可以导致人死亡，尤其是老年人。

A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is measured relative to the usual weather in the area and relative to normal temperatures for the season. Temperatures that people from a hotter climate consider normal can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area.