Different people react differently to heat. Some symptoms of heat exhaustion are headache, heat cramps, weakness, dizziness or nausea. You may have blurred vision, pass out, and suffer convulsions and ultimately death.
High humidity adds to the suffering. Your body will not cool down as much from sweating because the sweat cannot evaporate as efficiently. Everyone is more irritable and makes more mistakes when the temperature is above the comfort zone. Be aware of the conditions and be more careful.
In general at about 85° and 90% humidity most people begin to be uncomfortable. At about 92° and 90% humidity the body begins to react and heat exhaustion is possible. Whether or not a person can function in the heat is dependent upon your health, your physical condition and how hard you are working. Other factors are how much sleep you got the night before or how well rested you are. Stress is another factor in your ability to cope with the heat. A major factor is your acclimatization or how much time you spend working in the heat. Smoking, alcohol, or illness reduces your tolerance to heat.
What can you do to improve your tolerance?
Spend some time working outdoors in the heat. Always drink plenty of water. Some extra salt is necessary because salt is lost in sweat. Acetic acid increases your tolerance to heat. Acetic acid is in lemon aid and citrus fruits it is also in vinegar. Pickles and pickled products will help you feel more energetic in the heat.
What not to do!
Beer is not a Sports drink. Alcohol is a diuretic; this means it will dry you out more than quench your thirst. Coffee and soft drinks that contain caffeine will act the same way in your body. The more you drink, the more you will need to drink to keep up with your moisture loss through urination. A hang over is dehydration, about the same feeling as heat exhaustion complete with the headache and nausea.