Unlike some other biomes, wetlands do not have a characteristic climate. They exist in polar, temperate, and tropical zones, although usually not in deserts. However, they are very sensitive to changes in climate, such as a decrease in precipitation (rain, sleet, or snow). The amount of precipitation and changes in temperature affect the growth rate of wetland plants. Some wetlands are seasonal, which means that they are dry for one or more seasons of the year.
Temperatures vary greatly depending on the location of the wetland. Many of the world's wetlands are in temperate zones (midway between the North and South Poles and the equator). In these zones, summers are warm and winters are cold, but temperatures are not extreme. However, wetlands found in the tropic zone, which is around the equator, are always warm. Temperatures in wetlands on the Arabian Peninsula, for example, can reach 122°F (50°C). In northeastern Siberia, which has a polar climate, wetland temperatures can be as cold as -60°F (-5l °C).
The amount of rainfall a wetland receives depends upon its location. Wetlands in Wales, Scotland, and western Ireland receive about 59 inches (150 centimeters) per year. Those in Southeast Asia, where heavy rains occur, can receive up to 200 inches (500 centimeters). In the northern areas of North America, wetlands exist where as little as 6 inches (15 centimeters) of rain fall each year.
Source: "Wetland." U·X·L Encyclopedia of Biomes, Vol. 3. U·X·L, Detroit: 2000.