The American Red Cross declared an emergency blood shortage as the organization reported that blood inventory plummeted more than 25% in July.

The Red Cross said in a press release that heat had impacted almost 100 blood drives across the country in July as it braces for further disruptions caused by hurricanes.

The Red Cross said that the impending storms could, "result in additional blood drive cancellations and lower donor turnout, threatening an already low blood supply."

The weather-related impacts come on top of anticipated summer reductions in blood donations caused by vacation travel and other summer activities.

"Blood cannot be manufactured or stockpiled and can only be made available through the kindness of volunteer donors," the Red Cross said. "It’s the blood on the shelves now that helps during an emergency."

Type O blood rationed

Demands for blood from hospitals remained constant, according to the Red Cross, causing the organization to reduce distributions of type O blood to below hospital comfort levels.

Dr. Baia Lasky, division chief medical officer for the Red Cross, said that type O blood was the most common blood group used in transfusions.

"More than a quarter of all blood products each year are used in critical care and emergency room situations — those transfusions are only available because of the generosity of blood and platelet donors," Lasky said.

Red Cross reports lowest blood donor numbers ever

The disruptions come as only 6.8 million Americans gave blood once in 2023, the lowest number the Red Cross has seen. The organization said in a January press release that in the past 20 years donorship has fallen by 40%.

"When fewer people donate blood, even small disruptions to the nation’s supply are hard to overcome," the Red Cross said.

The record lows come over a year after the FDA removed restrictions on men who have sex with men giving blood.

The Red Cross is offering $20 Amazon gift cards to those who donate blood in August.