SAN ANTONIO — It's one of the more unfortunate things you'll hear reported on when you tune into the news—weather-related fatalities. 

There are four main threats that weather poses to human life: Lightning, tornadoes, flooding and heat. In recent years, heat has overtaken the top spot as the biggest weather-related killer in the U.S. 

On average, there are 130 deaths per year due to heat. Most of them could have been prevented, heightening the important of knowing the difference between heat exhaustion and heat stroke. 

Heat exhaustion, the less severe of the two, will manifest itself with symptoms of dizziness, excessive sweating, clammy skin, nausea or vomiting, and muscle cramps. You'll want to get to a cool place and drink water as soon as possible if you think you might be getting hit with heat exhaustion. 

The more serious ailment, heat stroke, has throbbing headaches, no sweating, a rapid heart rate and even loss of consciousness as its tell-tale signs. In those instances, you'll need to take immediate action and call 911. 

Make sure to stay hydrated and safe while outside this Memorial Day Weekend. It's gonna be a hot one in South Texas with heat index levels at cautionary levels, though they shouldn't reach extreme numbers.