Water
Water level is the first key variable in monitoring drought. Low water levels in streams, rivers, lakes and ponds, as well as declines in well water levels, a lessening of moisture in the soil and decreases in ground water availability all are signs of drought. Lack of precipitation for any great amount of time, a month or a season, calls for concerned response from environmental authorities. A decrease of snowpack in mountain peaks is another warning sign to farmers who depend on that snow melt to water their crop lands, orchards, pastures and gardens.
Plants
Signs of stress in plant life are another key parameter warning of coming drought. Drought stress signs in plants include wilting, a decrease in growth or no growth. Foliage appears yellow or yellow green, leaves die earlier, wood or bark cracks, stems and twigs die, flowers fail to open, and fruit drops early or doesn't fruit at all. Drought stress in plants happens when plants are not getting enough water, whether the water isn't sufficient for the plants' needs or because roots are not functioning adequately to absorb what water there is.
Animals
Livestock such as cattle, pigs, sheep and goats suffer both from lack of water and scorching temperatures. Farmers notice that cattle won't feed as much as the animals when they are simply too hot; cows in that condition do not give as much milk. Chickens will decrease egg laying. Warning signs in a herd of cattle include bunching together, heavy panting, slobbering, trembling and lack of coordination. Cattle may need to be culled from the herd. Animal stress is a warning sign of impending drought.
Heat/Fire
Higher temperatures usually go along with drying of the soil and lower water levels. As heat and dry climate conditions continue, the risk for fire increases. High temperatures, strong winds and dry thunderstorms potentially lead to wild fires, which can be sparked by lightening. In the 2009 drought in Texas, several hundred thousand acres burned.