The agency says it has less than a one-day supply available and has cut blood shipments to hospitals.
Summer typically is a tough time for the Red Cross to collect blood, mainly because of vacations, but lately, the heat also has cut into donations. Some blood drives in the region have been canceled because of the heat.
The Red Cross says all blood types are needed and asks residents to call 1-800-GIVE LIFE or visit www.newenglandblood.org to find out where they can donate.
The Red Cross has donor centers in Portland and Bangor, as well as a whole blood and platelet donation center at Central Maine Medical Center in Lewiston.