DENVER -- A large-scale study confirms what some migraine sufferers have suspected for years: Weather can play a role in their headaches.

Researchers looked at more than 7,000 patients who visited a Boston hospital with a complaint of headache over a 7-year-period.

They then looked at the air pollution levels, barometric pressure and temperatures for one to three days prior to these visits.

Researchers found a correlation between higher temperatures and risk of headache.

In fact, the risk of headache went up 7.5 percent for every 5 degree Celsius increase in temperature.

There was not any connection found between the amount of air pollution and the incidence of headaches.

"This confirms something that we’ve believed for a while, but have not been able to prove scientifically -- that the atmosphere has an effect on headaches -- particularly migraine headaches," said Dr. Dianne McCallister, the chief medical officer at Porter Adventist.

There are three major types of headaches:

1. Tension headaches. These are from the muscles on our head contracting, often due to stress. This type of headache is generally dull and over the entire head.

2. Migraine headaches. Caused by the blood vessels in the brain spasming, which can cause symptoms such as flashing lights in vision, pain on one side of the head and sensitivity to light and sound. This is usually on one side, but can be on both

3. Cluster headaches. These are more rare, but they usually come on very suddenly, are extremely painful, and are behind one eye. They tend to occur in groups and are associated with tearing in an eye and runny nose

Signs you may want to contact your doctor, include:

Sudden onset of a headache or very severe headache

Headaches after a head injury/bump to the head

Headaches that are associated with slurred speech, weakness or numbness or a stiff neck or fever

Headaches that get progressively worse with time or are triggered by coughing/sneezing/sudden movements

For more information, visit Porter Hospital's health library.