The savanna is a unique biome, defined by vast stretches of grassland interspersed with scattered trees. It represents a transitional zone between tropical rainforests and deserts, found primarily within the tropical latitudes (8° to 20° north and south of the equator). This biome covers large portions of Africa, South America, and Australia, characterized by predictable cycles of temperature change.
Defining the Savanna Climate
The savanna climate is often classified as Tropical Wet and Dry, defined by a pronounced annual rhythm of seasons. The savanna is characterized by an extreme distinction between a lengthy dry season and a shorter, intense wet season, unlike biomes closer to the equator that experience year-round rain.
This climate pattern results from the seasonal shift of the Intertropical Convergence Zone (ITCZ), a belt of low pressure near the equator. When the ITCZ moves away, the savanna falls under the influence of dry, high-pressure systems, initiating the dry season, which can last four to six months. The movement of this atmospheric system controls the humidity, cloud cover, and major temperature shifts throughout the year.
Seasonal Temperature Variations
The annual temperature pattern shifts significantly between the two primary seasons. During the peak of the wet season, average daytime temperatures often hover in the upper 70s to mid-80s Fahrenheit (25°C to 30°C). The increased cloud cover and high humidity provide a moderating effect through evaporative cooling, preventing the temperature from reaching its absolute annual peak.
The most intense heat is usually recorded in the late dry season, just before the first rains arrive. The absence of cloud cover or ground moisture allows temperatures to soar, frequently reaching 93°F to 100°F (34°C to 38°C) or even higher. This pre-rain period combines solar intensity with dryness. Conversely, the cooler, mid-dry season often sees monthly averages drop into the 68°F to 78°F (20°C to 25°C) range.
Daily Temperature Swings
Savannas are notable for their significant diurnal temperature range, the difference between the high and low temperature of the night. This daily swing is most pronounced during the dry season when the sky is clear and atmospheric moisture is minimal. Without the insulating blanket of clouds and humidity, the ground rapidly radiates its stored energy back into space after sunset.
It is not uncommon for a savanna day to reach 90°F (32°C) or more, only for the temperature to plummet to 55°F or 60°F (13°C to 16°C) overnight. This represents a daily range of 30 to 35 degrees Fahrenheit (17 to 20 degrees Celsius).