freezing rain
Meteorological term for rain that freezes upon contact with surfaces, forming a glaze of ice.
昨夜の雨氷で道路が滑りやすくなっている。
The roads are slippery due to last night's freezing rain.
Compound of 雨 (rain) and 氷 (ice), literally 'rain ice'. The reading うひょう is the on'yomi of both characters.