In a historic move, the New York Blood Center (NYBC) declared its second blood crisis of the season on July 8.
A previous emergency declaration was posted on May 26.
The NYBC has never before issued two blood emergency calls within a single summer, according to officials.
The two declarations differ in that the May emergency was fueled by traditional seasonal declines around Memorial Day while the second crisis stems from severe weather combined with national shortages.
Donor turnout is commonly disrupted during the summer months because of vacations, school breaks, and changing routines.
The NYBC said it employs sophisticated forecasting tools, donor engagement strategies, community partnerships, and operational programs to maintain a stable blood supply throughout the year.
In 2026, the seasonal challenges were exacerbated by extreme heat and storms that caused temporary donor center closures, and blood drive cancellations.
Additionally, a regional heat wave leading up to the July 4 holiday weekend resulted in two days' worth of blood supplies. The ideal revenue is seven days, according to the NYBC, in order to meet hospital demand.
"Normally, when one region experiences shortages, blood centers across the country can help support one another," New York Blood Center Enterprises Blood and Laboratory Operations chief operating officer Andrea Cefarelli said in a statement. "Unfortunately, blood inventories are low nationwide, limiting that safety net. We need our local communities to step forward now."
Despite about 62 percent of Americans being eligible, only 3 percent donate annually, according to American Red Cross data.
To maintain a healthy blood supply, New York Blood Center officials said they need to collect approximately 1,000 to 1,200 blood donations every day, which is about 7,500 donations each week.
During the week of the July 4th holiday, only 4,500 donations were collected compared with about 7,500 that would normally be collected during the same timeframe, which is some 3,000 fewer donations than expected.
NYBC is asking healthy, eligible donors to schedule an appointment as soon as possible.
The organization is also asking employers, community organizations, schools, faith-based groups, elected officials, media partners, and local leaders to encourage blood donation throughout the coming days.
Blood donors can donate every 56 days, and platelet donors can give up to twice per month.
The ways in which blood donations are used include helping trauma victims, cancer patients, individuals living with sickle cell disease and thalassemia, transplant recipients, and patients undergoing surgeries.