LAKE VICTORIA BASIN

The LVB climate is consistent with that of East

Africa. Major climatic features that regulate the

Basin include the El Nino Southern Oscillation,

the Quasi-biennial Oscillation, the Inter-Tropical

Convergence Zone and monsoon winds (Anyah and

Semazzi 2004). Together with Lake Malawi and Lake

Tanganyika, Lake Victoria has an influence on East

Africa’s climate (Song et al. 2004). The humid Congo

air mass, which originates in the tropical Congo

Rainforest, also affects the LVB climate (Anyah and

Semazzi 2004).

Despite the sporadic dust-storms and the occasional

haze from wood burning, the LVB enjoys a relatively

unpolluted atmosphere.

Temperature

Lake Victoria basin average temperatures reach a

maximum of about 28.7° C in February just before the

March equinox and reach their lowest in July after the

June equinox maximum. Minimum temperatures vary

from 14.7 to 18.2° C (Lake Victoria Basin Commission

2007). While there are wide differences between

cold season and warm season temperatures, studies

by Anyah and Semazzi (2004) show that average

temperature in the lake varies only slightly from

month to month.

Comparison of temperature records for the period 1950-

2000 and 2001-2005 show that maximum temperatures

have increased by an average of 1° C (Lake Victoria Basin

Commission 2007). Anyah and Semazzi (2004) noted a

significant jump in average temperatures in the basin

since the 1990s. Air temperature on the Ugandan side of

the lake was 0.5

C higher in the 1990s than in the 1960s

(Anyah and Semazzi 2004).

While the interactions between lake surface temperature

and rainfall amounts and distribution are complex,

there are indications that higher lake temperatures are

associated with increased rainfall, with models predicting

that some areas of the LVB could receive double the

current average rainfall when lake temperatures rise

by 1.5

C (Anyah and Semazzi 2004). Such an impact of

temperature increase would have significant impacts in

shaping the East Africa’s climate.

Rainfall

Average annual rainfall in the Basin ranges from 400 to

2,736 mm (Kizza et al. 2009). The minimum rainfall amount

was recorded at Ngudu while the maximum amount was

recorded at Bukoba. Recorded rainfall averages show that

received rainfall amounts are higher in the north to north-

eastern parts of the basin than the amounts received in the

southern portions of the basin (Kizza et al. 2009).

Atmospheric and Climatic Conditions

Figure 2.1: Average rainfall trends for Lake Victoria Basin since 1903

Source: Kizza et al. 2009