The No. 1 weather-related killer is heat - more than floods, hurricanes and tornadoes.

A Hudson Valley doctor says an average of 600 people die every year from its effects.

Northern Westchester Hospital Chief of Emergency Medicine Dr. James Dwyer says fatigue and nausea are some serious signs of heat-related illness.

“When it gets very severe, you see changes in mental status. Someone is not acting right, you can almost mistake it for a stroke,” says Dwyer. “So, when you see that and this hot dry skin, very beat red, hot, dry skin, and someone who is confused, that's a really concerning sign.”

The key is to limit your time outside to no more than 15 minutes.

And time is precious — do not hesitate to call for help.