The nights, although warm, are delightfully clear and serene at this season. Objects may be clearly distinguished at the distance of several hundred yards, so that one may even shoot by moonlight. The months of June and July offer very little variation in the weather or temperature. In August a suffocating heat reigns throughout the day, and at night it is useless to seek for coolness; a faint zephyr is succeeded by a calm of several hours. The atmosphere is heavy and oppressive, and the body, weakened by perspiration, becomes languid; the appetite fails, and the mosquitos, buzzing about the ears by day and night, perplex and annoy by their stings, while the fevers of the tropics attack Europeans with sudden and irresistible violence. This is the most sickly season for the European. The thermometer frequently exceeds 90 deg. The clouds exhibit a menacing appearance, portending the approach of the heavy autumnal rains, which pour down like a deluge. About the middle of September it appears as if all the vapors of the ocean had accumulated in one point of the heavens. The rain comes down like an immense quantity of water poured through a sieve; it excludes from the view every surrounding object, and in half an hour the whole surface of the earth becomes an immense sheet of water. The rivers are swollen and overflow their banks, the low lands are completely inundated, and the smallest brooks become deep and rapid torrents.
In the month of October the weather becomes sensibly cooler than during the preceding months, and in November the north and northeast winds generally set in, diffusing an agreeable coolness through the surrounding atmosphere. The body becomes braced and active, and the convalescent feels its genial influence. The north wind is accompanied (with few exceptions) by heavy showers of rain on the north coast; and the sea rolls on that coast with tempestuous violence, while the south coast remains perfectly calm.
When the fury of the north wind abates, it is succeeded by fine weather and a clear sky. Nothing can exceed the climate of Porto Rico at this season; one can only compare it to the month of May in the delightful Province of Andalusia, where the cold of winter and the burning heat of summer are tempered by the cool freshness of spring. This is considered to be the healthiest season of the year, when a European may visit the tropics without fear.
The small islands, destitute of wood and high mountains, which have a powerful effect in attracting the clouds, suffer much from drought. It sometimes happens that in Curacao, St. Bartholomews, and other islands there are whole years without a drop of rain, and after exhausting their cisterns the inhabitants are compelled to import water from the rivers of other islands.
"The land breeze" is an advantage which the large islands derive from the inequality of their surface; for as soon as the sea breeze dies away, the hot air of the valleys being rarified, ascends toward the tops of the mountains, and is there condensed by cold, which makes it specifically heavier than it was before; it then descends back to the valleys on both sides of the ridge. Hence a night wind (blowing on all sides from the land toward the shore) is felt in all the mountainous countries under the torrid zone. On the north shore the wind comes from the south, and on the south shore from the north.
Storms.—The hurricanes which visit the island, and which obey the general laws of tropical cyclones, are one of the worst scourges of the country. For hours before the appearance of this terrible phenomenon the sea appears calm; the waves come from a long distance very gently until near the shore, when they suddenly rise as if impelled by a superior force, dashing against the land with extraordinary violence and fearful noise. Together with this sign, the air is noticed to be disturbed, the sun red, and the stars obscured by vapor which seems to magnify them. A strong odor is perceived in the sea, which is sulphureous in the waters of rivers, and there are sudden changes in the wind. These omens, together with the signs of uneasiness manifested by various animals, foretell the proximity of a hurricane.
This is a sort of whirlwind, accompanied by rain, thunder and lightning, sometimes by earthquake shocks, and always by the most terrible and devastating circumstances that can possibly combine to ruin a country in a few hours. A clear, serene day is followed by the darkest night; the delightful view offered by woods and prairies is diverted into the deary waste of a cruel winter; the tallest and most robust cedar trees are uprooted, broken off bodily, and hurled into a heap; roofs, balconies, and windows of houses are carried through the air like dry leaves, and in all directions are seen houses and estates laid waste and thrown into confusion.
The fierce roar of the water and of the trees being destroyed by the winds, the cries and moans of persons, the bellowing of cattle and neighing of horses, which are being carried from place to place by the whirlwinds, the torrents of water inundating the fields, and a deluge of fire being let loose in flashes and streaks of lightning, seem to announce the last convulsions of the universe and the death agonies of nature itself.
Sometimes these hurricanes are felt only on the north coast, at others on the south coast, although generally their influence extends throughout the island.
In 1825 a hurricane destroyed the towns of Patillas, Maunabo, Yabucoa, Humacao, Gurabo, and Caguas, causing much damage in other towns in the east, north, and center of the island. The island was also visited by a terrible hurricane in 1772.