The monthly range of temperature is the difference between the highest and lowest daily temperatures for the month.
This means that for each day of the month, the highest temperature and the lowest temperature are recorded. The range of temperature for the month is then calculated by subtracting the lowest temperature from the highest temperature for the month.
For example, if the highest temperature recorded during the month was 30°C and the lowest temperature recorded was 10°C, the range of temperature for the month would be:
30°C - 10°C = 20°C
Therefore, the correct answer is "differences between the highest and lowest daily temperature for the month."