PORTLAND — The American Red Cross encourages all eligible blood donors to make an appointment to donate blood soon to help prevent a shortage.

During the summer months, on average, about two fewer donors give blood at each Red Cross blood drive than what is needed to meet the needs of patients. Vacations and summer activities are among the reasons regular donors may not find the time to give. But, patients don’t get a vacation from needing blood — the need is constant.

August blood donation opportunities are as follows.

Friday, Aug. 8, 9 a.m. to 3 p.m. at Mechanic Savings Auburn, 100 Minot Ave, Auburn.

Monday, Aug. 11, 1 to 6 p.m. at Hilton Garden Inn, 14 Great Falls Plaza, Auburn.

Tuesday, Aug. 12, noon to 6 p.m. at Murray Hall, 69 Main St., Livermore Falls.

Thursday, Aug. 14, 1 to 6 p.m. at Saint Francis Church, 130 Route 133, Winthrop; and 11 a.m. to 5 p.m. at Point Sebago, 261 Point Sebago Road, Casco.

To learn more and make an appointment to donate blood, visit redcrossblood.org or call 1-800-RED CROSS.

A blood donor card or driver’s license or two other forms of identification are required at check-in. Individuals who are 17 years of age (16 with parental consent in some states), weigh at least 110 pounds and are in generally good health may be eligible to donate blood. High school students and other donors 18 years of age and younger also have to meet certain height and weight requirements.