Weather and Climate of Cape VerdeThe Cape Verde Islands are located west of the Sahel zone (the Savannah area located between the Sahara Desert and Tropical Africa) with a climate that may be defined as Dry-tropical. This location, on the very limit of the tropical rain-belt, means that the Islands do not always receive a monsoon. In fact, it is not unknown for some Islands to go for years at a time without receiving any significant rain.
Sea-water Temperatures vary between about 21°C in February to about 26°C in September, temperatures in shallow waters will be a few degrees higher.
Average Daily Maximum Temperatures vary between about 24°C in January and 30°C in August/September. Daily Minimums are about 19°C in winter and 24°C in summer.
If the rains do arrive, it is usually between August and October (the "Rainy Season"), when it can be uncomfortable at times with high temperatures and high humidity. The other season is between December and June, when the north-easterly Trade Winds are prevalent, during this season, only altitudes above about 600m tend to receive regular rain. The North-eastern slopes of these high mountains often receive several times the amount of rain that south-westerly slopes lying in rain shadow receive.
The clearest skies tend to be between February and June, with very little rainfall during these months - the Island of Sal receives an average of 0.0mm in May! When and if rain does arrive, it can be very heavy - often half the year's rain can fall in a single storm.
Dust from the Sahara
Another factor that occasional affects the Islands is the Harmattan wind, laden with dust from the Sahara. This normally occurs between November and March and is similar to the "Calima" that affects the Canary Islands.
The Canary Current from the north has a cooling effect on the Cape Verde Islands, making air temperatures more bearable than might otherwise be expected at this latitude. Conversely, the Islands do not receive the cold upwellings that affect the west African coast, so while air temperatures are cooler than in nearby Senegal, the sea is actually warmer.
Although Hurricanes often begin their formation in the waters around the Cape Verde Islands, they rarely reach hurricane strength close to the Islands. A typical Cape Verde-type hurricane develops in the area south of the islands following a tropical wave from mainland Africa (during the rainy season). The storm will then strengthen as it crosses the warm waters of the tropical Atlantic before reaching the Caribbean or Florida.