Rosario weather is warm and humid throughout most of the year. It is classified as temperate Pampas, it is that the four seasons are fairly defined, although its winter is fairly mild, short and irregular: during this season are observed both cold and cool days, and even warm afternoons. It is very common during the winter months to have a good number of days where the maximum temperature exceeds 20 degrees.

Summers are hot, and high humidity can sometimes create suffocating days. There's a hot season from October to April, with temperatures from 18°C (64°F) to 36°C (97°F), and a cool season, varying between early June and the first half of August, with minimum average of 5°C (41°F) and average maximum of 16°C (60°F), with annual average temperatures ranging between 11°C minimum (51°F) and 24°C maximum (76°F). It rains more in summer than in winter, with an aggregate rainfall between 800 and 1300 mm per year.