Drought The Palmer Drought Severity Index Annual Mean 1950-1999

Regional Climate Centers (RCC) Palmer Drought Severity Index (PDSI: drought index). Recent 10-year climatology for drought in all months, 1950-1999.

Drought is one of the most consequential aspects of variation in precipitation and temperature patterns in terms of its impacts on natural ecosystems and human systems. The production of food and clean water can be strongly affected, as can forest products production, outdoor recreation, ecosystem processes such as wildland fire, and many other processes affecting ecosystem services. Having a grasp on recent ranges of variability in drought conditions can provide a context for understanding ongoing and future climate change and its impacts on ecosystem services. Although predicting future drought conditions is fraught with uncertainties, extreme precipitation highs and lows are both becoming greater in many regions. As a result, some regions may experience more frequent drought and flood conditions, with stronger variation over time becoming a “new normal.”