Standardized Precipitation Index (SPI)

The Standardized Precipitation Index (SPI) is a tool used to measure and track drought or wetness conditions based on rainfall data. It compares current precipitation levels to historical records, standardizing the result so that it can be easily interpreted across different regions and timeframes. Positive SPI values indicate wetter-than-normal conditions, while negative values signify drier-than-normal conditions. This helps scientists and planners understand whether observed rainfall levels are unusual, guiding water resource management, agricultural planning, and drought mitigation efforts efficiently.