The American Red Cross is warning of a critical blood shortage as the nation enters what it calls “trauma season.” 

Officials say hot weather, increased travel and outdoor activities can lead to more accidents and a higher need for blood.

Donations have dropped in recent weeks, with fewer appointments and fewer collections from schools during summer break.

The Red Cross is urging people to donate this month and is offering a free movie ticket for donations made between July 13 and July 31.