The summers throughout the transition province are hot, with little rain in the western portion, but refreshing showers and occasional destructive storms in the humid eastern portion. Owing to the latitude of the main transcontinental belt of the province, the number of hours of sunlight each day in summer is increased beyond what it is in the main portions of the austral provinces, thus favouring the growth of vegetation. There is also a lengthening of the morning and evening duration of twilight, and magnificent sunrises and sunsets are frequent. The mean summer temperature is in the neighbourhood of 70 deg. F., but hot spells, lasting for days, and even weeks, are of common occurrence. During these trying and frequently unhealthy intervals the temperature in the shade reaches or even exceeds 100 deg. F., and sunstrokes or prostrations by reason of the heat, particularly in the cities, are numerous. The four seasons of the year are better marked and have more pronounced characteristics in this division of the continent than in any other, and it is the region of greatest seasonal climatic changes as well as of marked weekly and even daily variations in weather conditions. The most delightful months to most people are May, when the returning migratory birds are nesting, the trees unfolding their many tinted leaves, and the air laden with the perfume of multitudes of blossoms, and October, when the rich colours of ripened leaves give to the forests a marvellous variety and brilliancy of colour and the tranquil, hazy atmosphere is undisturbed by storms for days and even weeks together. This annual period of tranquil weather, extending frequently far into November, is known as Indian summer.