A UN report also warned that water-borne diseases like cholera pose a threat, with 600 cases diagnosed in the first 10 weeks of the year.
The worst-hit provinces are in the south — Cunene, Kuando Kubango and Moxico — but heavy rains have damaged buildings crops in other regions, including the capital Luanda.
In Cunene, 130 000 hectares of farmland have been destroyed and as many as 300 000 cattle are at risk because they are cut off from grazing areas.
Local media have also reported that distressed elephants are tearing up flooded fields, and the UN report said all provinces are concerned about limited food reserves and increased malnutrition.
"Food security is always an issue in Cunene. It is very dry and arid most the year but then when the rains come, they come with such force they wash away a lot of crops which makes things worse," Juan Sheenan, head of the Catholic Relief Service (CRS) in Angola, told AFP.
So far, 22 people are reported dead in the floods, mostly from drownings, but two children in Kuando Kubango were killed by alligators, state media said.
In Luanda, heavy rains caused traffic chaos and destroyed newly-laid tarmac on roads, leaving behind deep open trenches which cars have been falling into.
In one night last week, nearly 200 buildings, including medical centres, in the suburb Viana, lost their roofs.
Sapa
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