It sounds like you probably had heat exhaustion, which is a condition in which rising body temperature and dehydration together conspire to create a state in which the affected person feels fatigued and dizzy. There may also be nausea and vomiting
. Heat exhaustion is a warning sign that you are getting overheated and dehydrated. It can usually be treated by getting out of the sun, resting, and drinking fluids to rehydrate yourself.
Heat stroke, on the other hand, is a much more serious illness that occurs when heat exhaustion and dehydration are allowed to progress. In heat stroke, the affected person becomes delirious or confused, absence of sweating, rapid pulse, and difficulty breathing. Heat stroke is a medical emergency which is life threatening and requires immediate attention in an emergency room.
In order to prevent heat exhaustion in the future, the most important thing is to stay well hydrated while outdoors. You also should limit the amount of time you spend in direct sunlight. If you start to feel fatigue of lightheaded these are signs that you are getting dehydrated and that you need to get out of the sun right away. I also recommend that you talk to your primary care doctor
for more information.