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Climate
The Zambezi River Basin’s climate is strongly
influenced by prevailing wind systems that
include the South-easterlies, the Congo air
mass, the North-easterlies and the Inter-Tropical
Convergence Zone. The presence of large
water bodies, Lake Malawi/Nyasa/Niassa, Lake
Kariba and Lake Cahora Bassa, also plays a role in
modifying weather conditions.
The temperature across the river basin varies
according to elevation and, to a much lesser
extent, latitude. Mean monthly temperatures
for the coldest month, July, vary from below
13°C for higher elevation areas in the south of
the basin to 23°C for low elevation areas in the
delta in Mozambique. Figure 1.7 indicates that
the coolest area is the south-eastern part of
the basin, part of which is in Zambia and the
other part is in Zimbabwe. Ground frost occurs
locally in some parts of the basin between July
and August as daily minimum temperatures in
higher elevation areas can be below 0°C.
Mean daily temperatures for the warmest
months (October and November) vary from
around 23°C in the highest elevation areas, to
31°C for the lower parts of the Zambezi Valley
(Chenje 2000). The basin experiences a high
daily range of temperatures, with an average
range of about 10°C in the rainy season and as
much as 20°C in the dry season in the southern
parts of Zambia and northern Zimbabwe. Due
to the high temperatures, the annual total
evaporation ranges between 5 to 10 mm per
day. As a result, about 65 per cent of all the
Figure 1.6
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Zambezi River Basin average rainfall
Sources: Denconsult 1998. ZACPLAN Sector Studies:
Introductory Volume. Final Report. Southern African
Development Community and Zambezi River Authority,
Lusaka; Chenje, M. (Ed.) 2000. State of the Environment
Zambezi Basin 2000. SADC/IUCN/ZRA/SARDC,
Maseru/Lusaka/Harare
NAMIBIA
Mean annual rainfall
Millimetres
ANGOLA
BOTSWANA
500 600 700 800 900 1 000
1 500
ZAMBIA
ZIMBABWE
MOZAMBIQUE
TANZANIA
MALAWI
DEMOCRATIC REPUBLIC
OF CONGO
© SARDC
© SARDC