气温突降.The temperature suddenly dropped.图表上的曲线突降之后逐渐趋于平稳.The graph flattens out gradually after a steep fall.在这次气温突降时节,要保证孩子们穿得暖和.Be sure the children are wrapped up in this sudden cold weather....

“突降”的英语可以翻译为：light，nose dive ...