Just because a region is hot and dry doesn't necessarily mean it is going through a drought. • Droughts are becoming longer and more extreme around the world. A drought is caused by drier than normal conditions that can eventually lead to water supply problems. • Temperatures are rising world-wide due to greenhouse gases trapping more heat in the atmosphere. • Tropical storms becoming more severe due to warmer ocean water temperatures. Causes of Drought Rainfall or Precipitation Deficiency Droughts take place whenever there is prolonged periods of rainfall deficiency for a season or more and usually when there is a lack of anticipated rainfall or precipitation. Lack of water in river systems and reservoirs can impact ... Meteorological Drought. While droughts can be defined in many ways, three main drought types are commonly discussed: Hydrological Drought. Really hot temperatures can make a drought worse by causing moisture to evaporate from the soil. Many watersheds experience depleted amounts of available water. Droughts only occur when an area is abnormally dry.