In this coastal region the extremes of temperature are 107·6° in summer and 41° in the winter; but these temperatures are both exceptional. However, a temperature of 95° is very usual on summer afternoons. It is a very unusual thing for the mercury to fall below freezing-point in winter or to remain there. Snow is also a very rare phenomenon, only to be seen perhaps once in five years.
A peculiarity of the Argentine climate in general is that the temperature will change very rapidly during the day, or even during a few hours; the change representing sometimes a difference of more than 36°, especially in the spring, which is the most usual season for these rapid variations.
The climate of the coast region——that is, of a country consisting almost entirely of plains——is, in general, influenced by the winds, which blow in gales at all seasons. Northerly and southerly gales are the most common; the first especially are very frequent. In Buenos Ayres one finds, during the summer, an alternation of sea and land breezes; the one during the day, the other during the night.
The northerly winds are always hot and even suffocating; they influence the nervous system, afflicting some people with neuralgic troubles. When these winds blow, the air is charged with electricity, until, the tension of the atmosphere having grown insupportable, a tempest comes to restore the equilibrium, to give place to another wind, coming from the south-west, and known as the _pampero_. This wind does not often last long, but it attains a velocity equal to that of a full hurricane. The _pampero_, so called because it is formed in the region of the pampas, is a wind full of ozone, and as such plays its part in disinfecting the vitiated air of the urban centres. But the effects of the _pampero_, and especially of the south-westerly winds, on the Rio de la Plata, where they produce a violent swell, are sometimes terrible.
As for the rain, there is no regularity in its fall; which naturally tends to render the results of culture and of cattle-breeding variable. Rains are more frequent in summer and autumn than at other times; while the least rainfall is that of winter. At Buenos Ayres it is rare for a month to pass without rain, which is often torrential, and accompanied by hail.