Nicaragua’s climate is tropical, with temperatures determined largely by elevation. The coastal regions have a hot climate, with a mean average temperature of 81°F. In the central highlands, the temperature varies between 60° and 80°F. The rainy season occurs from May until early November.
The weather on the top is cool, fresh and sometimes wet; a light jacket for rain and wind is essential.
Nicaragua has a predominantly tropical climate, alternating between two seasons: rainy and dry (winter and summer). In the Central Region the rainy season lasts from May to October. The dry season occurs from November through April. During December the weather is more temperate. The warmest months are March, April and May, Nicaragua’s "sea season". The weather is much more temperate in the Central and Pacific regions.
The dry season at Darien is the time when trade winds blow fresh from the north and a heavy blue sea breaks all along the coast. Little rain falls, except in the mountains. Temperatures range in the low eighties; the sky is spotlessly clear day and night.
The line of march was to be over the abrupt green mountains that rise only a few miles in from shore. Selfridge would head for the Caledonia gap, which, from the bay, appears lower than it is and might well be taken even by an experienced observer as the perfect place for a canal. It was what had attracted Dr. Edward Cullen originally.