Excess rain or snowpack can eliminate habitat by flooding, thus decreasing the vector population size.

Low rainfall can create habitat by causing rivers to dry into pools (dry season malaria).

Decreased rain can increase container-breeding mosquitoes by forcing increased water storage.

Epic rainfall events can synchronize vector host-seeking and virus transmission.

Increased humidity increases vector survival; decreased humidity decreases vector survival.


Few direct effects but some data on humidity effects on malarial parasite development in the anopheline mosquito host.

Vertebrate host

Increased rain can increase vegetation, food availability, and population size.

Increased rain can also cause flooding and decrease population size but increase contact with humans.

Decreased rain can eliminate food and force rodents into housing areas, increasing human contact, but it can also decrease population size.

Increased sea level

Alter estuary flow and change existing salt marshes and associated mosquito species, decreasing or eliminating selected mosquito breeding sites (e.g., reduced habitat for Culiseta melanura).


aThe relationship between ambient weather conditions and vector ecology is complicated by the natural tendency for insect vectors to seek out the most suitable “microclimates” for their survival (e.g., resting under vegetation or pit latrines during dry or hot conditions or in culverts during cold conditions).

SOURCE: Gubler et al. (2001).

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