Extreme heat is the deadliest weather-related hazard in the United States, leading to spikes in emergency room visits and hundreds of deaths every year.

Health experts say recognizing the signs of heat-related illness early is one of the most effective ways to prevent serious medical emergencies.

Heat exhaustion can occur when the body loses too much water and salt, often through heavy sweating during high temperatures.

Symptoms may include headache, nausea and irritability — all early warning signs that the body is struggling to cool itself.

If symptoms worsen or if someone begins showing signs of heat stroke, emergency medical treatment is critical. Heat stroke is a life-threatening condition, and symptoms can include confusion, slurred speech and changes in mental status.

Officials urge people to stay hydrated, limit strenuous activity during peak heat and check on vulnerable neighbors as temperatures climb.