U.S. Drought: Weekly Report for September 5, 2023

According to the September 5, 2023 U.S. Drought Monitor, moderate to exceptional drought covers 30.2% of the United States including Puerto Rico, an increase from last week’s 28.8%. The worst drought categories (extreme to exceptional drought) increased from 6.2% last week to 7.5%.

While the upper-level circulation over the contiguous U.S. during this U.S. Drought Monitor week (August 30–September 5) continued to be dominated by a strong ridge of high pressure, several low-pressure systems attacked the ridge as well. 

Hurricane Idalia slammed into the Florida Gulf coast early in the week and spread a path of heavy rain and cooler-than-normal temperatures across the Southeast. Upper-level troughs of low pressure moved across the West, leaving behind above-normal precipitation and below-normal temperatures. 

Other troughs moved across the top of the ridge, with their surface low-pressure systems and cold fronts mostly keeping to the U.S.-Canadian border region. With the ridge dominating the weather, much of the Southwest, Great Plains, Midwest, and Northeast had a dry week, with excessive heat continuing across the Plains and Upper Midwest. The ridge extended eastward across the Caribbean and westward into the North Pacific, resulting in another dry week for Hawaii, Puerto Rico, and the U.S. Virgin Islands. Alaska had a mixed temperature and precipitation anomaly pattern. The above-normal rain contracted abnormal dryness and drought or reduced its intensity in the Southeast and interior West. But abnormal dryness and drought expanded or increased its intensity in the Southwest, Great Plains, Midwest, Mississippi Valley, and parts of the Mid-Atlantic. 

Nationally, expansion exceeded contraction, so the nationwide moderate to exceptional drought area increased. Abnormal dryness and drought are currently affecting over 117 million people across the United States including Puerto Rico—about 37.8% of the population.