According to statistical information obtained from the Centers for Disease Control, approximately 3,442 heat related deaths were reported during 1999-2003. 
Someone can have a heatstroke from exposure to high temperatures and it is most often combined with dehydration. The medical definition of heatstroke is when the core temperature of the human body is greater than 105 degrees Fahrenheit.
Here are the ten most common signs and symptoms of a heatstroke you need to watch out for. If a person has spent a lot of time in the heat and experiences any of the following signs or symptoms, it is important to seek immediate medical attention:
1. Extremely hot skin
When someone has extremely hot, dry and red skin, it could be signs of a heatstroke. If skin is hot to the touch and a person’s internal body temperature has risen to 105 degrees Fahrenheit or higher, it is a condition which requires emergency medical attention.
2. Fainting and Dizziness
In addition to having a core temperature higher than 105 degrees Fahrenheit, people with heatstroke will experience dizziness and fainting. If someone has spent a great deal of time in the sun and experiences these symptoms, it is very important to drink a lot of fluids for rehydration.
Experiencing nausea is another sign to watch out for. Being constantly nauseous, in combination with dizziness, can mean your condition is worse than originally believed. Consuming a lot of fluids will help to treat the nausea and it is recommended to find shelter under the shade.
Having a nauseous feeling is one thing. If someone’s nausea has progressed into vomiting, it is a definite sign of heatstroke and emergency medical attention is a must. It is important to try to rehydrate the body with electrolytes and water as soon as possible.
5. Extreme fatigue
Being in the heat all day long can be physically draining to anybody. However, if a person is experiencing other symptoms on this list, accompanied by extreme fatigue, it can be a sign of heatstroke. It is always best when a person exhibits the signs of a heatstroke to seek medical help, because it can prevent the condition from becoming worse.
6. Rapid heart rate
Having a rapid heart rate after spending a day in the sun can be indicative of something serious. If you are having a rapid heart rate, along with other symptoms, it is a situation which requires urgent medical care. When it comes to cardiac symptoms, it is always very important to err on the side of caution and be checked out.
7. Mental confusion
People who are experiencing a heatstroke will often feel faint and dizzy, but mental confusion is another sign. If a person is experiencing mental cloudiness and confusion, it could be indicative of a heatstroke.
8. Not producing sweat
One of the main differences between heat exhaustion and heatstroke is that a person stops sweating. If someone has spent too much time in the sun, it is normal to feel hot and sweaty. However, if a person has developed a heatstroke, there will be a lack of sweat, in spite of feeling extremely hot.
Having a seizure is a very serious symptom of heatstroke. A seizure can present quickly and have few warning signs. If a person has a seizure, it is very important to get them to the hospital immediately, without delay.
10. Extreme headache
If a person has spent a lot of time in the sun and has a bad headache, it may be due to suffering a heatstroke. It is common for people to have a small headache after spending time in the hot outdoors, but if it’s really bad especially with other symptoms listed, you might want to go back inside.
Heatstroke is a preventable condition. According to the Mayo Clinic, there are certain steps a person can take to keep it from happening.  A person should wear lightweight, loose clothing which will not hug the body tightly and retain heat.
It is important to drink plenty of fluids when out in the heat for long periods of time, because it will keep the body well hydrated. If you notice you are becoming overly hot or displaying any of the warning signs of a heatstroke, it is important to get cooled down and if necessary seek medical attention when warranted.