Weather is probably a major factor when you plan your trip to Buenos Aires, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and September, with an average temperature of 20°C, while the coldest months are January and July, with an average of 20°C. The rainiest months in Buenos Aires are April, November, October and December, with each month seeing an average of 300 mm of rainfall.