Meaning of RAINFALL in English
BAD : There was no rainfall for over three months.
GOOD : There was no rain for over three months.
GOOD : It didn't rain for over three months.
rainfall = the amount of rain that usually falls in an area during a certain period: 'The whole region has a very low rainfall at this time of the year.' Note that rainfall is mainly used in technical styles.
Longman Common Errors English vocabulary. Английский словарь распространенных ошибок Longman. 2012