The climbers had to contend with harsh weather conditions.

contend 是动词，由前缀 con-（加强语气）和词根 tend（"伸展、趋向"）组成，原指"奋力伸展、努力争取"。contend with 是固定搭配，意思是"不得不应对（困难）"、"与…斗争"。在这里指登山者需要与恶劣天气进行对抗。