Santa Rosa de Osos: are you wondering about the weather you might find during your holiday? Befor organizing a holiday we always think about the wheather we might find when we get there. In Santa Rosa de Osos the average yearly temperature is 16°C. During the hottest month, which in this case is March, the temperature can get up to 17°C. Instead the coldest month is January, reaching a minimum temperature of 16°C.