Our bodies actually need time to become accustomed to the rising temperature.
The heat may be a shock to many people’s systems -- take the heat seriously and watch out for these red flags.
The heat doesn't mean life stops, so a lot of people either have to, or choose to, stay active outdoors. The main way we cool ourselves is by sweating. As the sweat evaporates it cools us down. That's why a "dry heat" is more tolerable than heat with high humidity. Of course, the price of sweating is a loss of fluid and body salts, which is what causes some of the problems we see.
Your body does its best to keep your temperature in a normal range, but if you keep generating more heat through activity it puts an extra strain on your body.
How you feel
The first red flag that the heat is taking a toll is obvious in how you feel. If you're fatigued, or sluggish and you have a headache or feel like your heart is pounding -- especially with lightheadedness -- you should take the hint and cut back.
Bathroom trips, urine color
Another red flag may seem indelicate, but it's very practical and important. If you find that you are going to the bathroom less often to urinate and your urine is a concentrated darker yellow -- not the more normal yellow -- it means your kidneys sense that you are dehydrated and they're holding on to as much water as they can.
You should listen to what your kidneys are trying to tell you -- it's an early sign of dehydration and you need more fluid.
When we lose fluid and electrolytes from sweating it can cause the next red flag -- muscle cramping -- this can occur whether you're being active or not -- but it's more common with activity.
As someone's body temperature becomes dangerously high the biggest red flag to watch for is confusion and blacking out, almost like being drunk. When it gets to that stage the major concern is the start of heat stroke. That's an emergency and the person should go to a hospital.
Staying well hydrated is really the most critical thing. Most people get enough salt in their diet that special rehydration drinks aren't needed. Plain old cold water is fine. It is important to pre-hydrate, though, at least a half hour before exertion in the heat you should start fluids so you don't falll behind with fluid losses.