Although most people consider the cold and flu season to span from November through February, these ailments are not limited to the winter months. Winter is not the only time that people get colds but they are more prevalent at that time. Colds happen all year round.
According to Alternative Medicine, compiled by the Burton Goldberg Group, cold and flu viruses are the most common afflictions attacking the body's upper respiratory tract, with 40% of the U.S. population being stricken with flu each year. The editors explain that, "the common cold and flu are believed by most physicians to be caused by exposure and susceptibility to a variety of common viruses."
Colds and flu are more common in the winter months because people congregate inside, with the doors and windows shut tight, allowing viruses to increase and spread in close quarters. So cover your mouth when you cough This may help some but you can't stop people from touching doorknobs, rub their eyes, shake hands and pass the g ...more

It is possible if our system is weak

Natural.

Yes ....sometimes we do get cold during winter.