(CNN) -- You dread this: Runny nose, scratchy throat, maybe a cough. And worse, it's 80 degrees outside.
Most of us know it as the summer cold. But in fact it's probably not.
A true cold is a virus with symptoms that last up to 10 days, with the first two to three days being the most contagious. These viruses exist year-round, but are more common in the colder months.
Allergies to tree and grass pollens and outdoor molds can cause cold-like symptoms in the summer. Congestion, itchy eyes, scratchy throat and runny nose are common complaints.
"If you tend to get those same symptoms every year around the same time, allergy is the probable cause," said Dr. Peter Greenspan, pediatrician with MassGeneral Hospital for Children in Boston, Massachusetts.
Young children are more susceptible to cold viruses because they have not had previous exposure to them, Greenspan said. They are also in contact with other children a lot, and may not take the same hand-washing, sneeze-covering precautions as adults.
They are too young to take over-the-counter medications, but the symptoms go away on their own, Greenspan said.
For adults who want sinus relief, a doctor may recommend saline irrigations through the nose -- such as the neti pot -- nasal steroid sprays or antihistamines, said Dr. Alexander Chiu, associate professor of otorhinolaryngology at the University of Pennsylvania School of Medicine in Philadelphia.
But such treatments are for relieving symptoms, not curing them, Greenspan said. Colds go away on their own and allergies subside when the offending pollen diminishes with the season.
This spring was particularly nasty for allergies, doctors said. The pollen counts are going down now, however, and the next major allergy season won't start until fall, Chiu said.
Doctors use the term "vasomotor rhinitis" to describe the cold-like symptoms that many people get not because of allergies or a virus, but for some unknown cause, Chiu said.
Some people are naturally sensitive to dramatic temperature changes and may get the sniffles from going in and out of air-conditioned and warm environments, said Chiu.
But such temperature shifts do not promote cold viruses, so don't blame the air conditioning, Greenspan said. For allergy sufferers, air conditioning may help alleviate symptoms.
"Some people may feel better or worse in different kinds of environments," he said. "It's a very individual kind of thing."
From his pediatrics practice, Greenspan has noticed that a cold virus has been going around, with coughs that last several weeks, Greenspan said.
But Chiu, based in Philadelphia, said people who have sinus symptoms this time of year probably do not have colds.