Evaluating Current U.S. Evaporative Drought Demand Index

Highlight: Dangerous ED4 Evaporative Drought Demand Index Conditions Are Widespread; May 2025 Drought Risk Outlook

Fig. 1: The most recent U.S. evaporative drought demand index analysis.

Discussion: As a review, the Evaporative Drought Demand Index (EDDI) can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk by providing near-real-time information on the emergence or persistence of anomalous evaporative demand in a region.

Based on the most recent analysis, ED1 conditions were observed in the Los Angeles Basin (Fig. 1). However, a large and intense dangerous D4 region is just to the east where Santa Ana wind generates and extends westward to the coast. Proximity of the dangerous D4 EDDI region to Los Angeles contributed to rapid spread and intensity of the fires.

Elsewhere across the U.S., dangerous ED4 conditions are widespread to include Nevada to New Mexico, the Midwest U.S., Northeast Corridor Coastal areas, and southwestern Florida. Once again, the D4 areas are susceptible to developing or worsening drought, including flash drought plus elevated fire risk. Of course, the warm season is normally when these risks can be realized.

Current U.S. soil moisture anomaly analysis identifies the extreme dryness on the southwest California Coast and eastward through Texas (Fig. 2). A large area of dry soil extends across the northern half of the Great Plains to the Upper Midwest and Great Lakes region. Dry soils have re-emerged during early January in the Southeast States and the Northeast U.S. Corridor.

The seasonal soil moisture change indicates a much wetter trend across Northern California and the Mid-south U.S. (Fig. 3). Drier soil conditions are apparent in coastal southern California, Florida, and the Carolinas regions.

The NOAA/CAS U.S. soil moisture anomaly outlook for May 2025 indicates favored areas for elevated drought risk with hydrological/agricultural/fire risk impacts is the Southwest U.S. including Southern California, much of the Gulf region, and New York/Pennsylvania to southern New England (Fig. 4). Risk areas also include parts of the Midwest States to the northern Ohio Valley and northern Utah.

Fig. 2: The NOAA/CPC daily U.S. soil moisture anomaly analysis.

Fig. 3: The NOAA/CPC seasonal soil moisture anomaly change analysis.

Fig. 4: The NOAA/CPC soil moisture anomaly forecast for May 2025.