And the american red cross is sounding the alarm tonight about a critical shortage in the nation's blood supply. The worst in more than a decade and there's a surprising reason why. Abc's ryan owens... See More
And the american red cross is sounding the alarm tonight about a critical shortage in the nation's blood supply. The worst in more than a decade and there's a surprising reason why. Abc's ryan owens explains. Reporter: Severe weather can knock out power, blow down trees and flood streets. But this year all those summer storms hit something else, the nation's blood supply. The american red cross says the supply has dropped to its lowest level in 15 years. It puts our community in a very difficult situation. Patients don't get vacations. They're in the hospital, and they need blood. Reporter: Summer is always slow, but the red cross says this month's severe weather canceled many blood drives. What's more, doctors say the extreme heat is keeping many regular donors at home this summer. You never know who is going to be the next person that needs blood. It might be your next-door neighbor. It might be your child, and it might be you. Reporter: Hospitals may soon cancel some elective surgeries or even postpone more serious procedures because they require so much blood. Patients who are having elective procedures are also encouraged to donate blood two or three months ahead of time for their surgery to ensure that their procedure is not canceled. Reporter: August is traditionally the slowest month for blood donations, but the red cross is hoping by sounding the alarm now, they can weather this storm too. Ryan owens, abc news, los angeles.
This transcript has been automatically generated and may not be 100% accurate.