What is a Heat Advisory
A heat advisory is a weather alert issued by the National Weather Service when dangerously hot conditions are expected in an area. It means the heat index (the temperature it feels like when you combine air temperature and humidity) will reach levels that can cause heat-related illness. During a heat advisory, people should take precautions like staying hydrated, limiting outdoor activity, and checking on vulnerable people.
What is a Heat Warning
A heat warning is a more serious alert issued when extreme heat is expected to pose a significant threat to public health and safety. Heat warnings indicate dangerously high heat index values that make heat stroke and other severe heat-related illnesses much more likely. During a heat warning, people should take extra precautions and may be advised to stay indoors or seek air-conditioned spaces.
Key Differences
The main difference between a heat advisory and a heat warning is severity. Heat advisories are issued for less extreme heat conditions, while heat warnings are issued for more dangerous and extreme heat. Heat warnings pose a greater threat to health and require more urgent action. Think of an advisory as a caution sign and a warning as a stop sign. Both are important, but a warning means the danger is more serious.
Temperature Thresholds
Heat advisories are typically issued when the heat index is expected to reach 99 to 103 degrees Fahrenheit. Heat warnings are usually issued when the heat index is expected to exceed 103 degrees Fahrenheit or higher. However, these specific temperatures can vary by region based on what that area normally experiences, since people in hotter climates may be more adapted to extreme heat.
Health Risks During Extreme Heat
Both heat advisories and warnings are issued because extreme heat can cause serious health problems. Heat exhaustion can cause heavy sweating, weakness, and dizziness. Heat stroke is more dangerous and can cause confusion, loss of consciousness, and organ damage. Certain groups like elderly people, young children, and people with heart or breathing problems are at higher risk during extreme heat.
How to Stay Safe
During a heat advisory or warning, drink plenty of water even if you're not thirsty, avoid strenuous outdoor activities, stay in air-conditioned spaces when possible, and check on family members and neighbors who may be vulnerable. Never leave children or pets in parked cars. Wear light-colored, loose-fitting clothing and use sunscreen. If you experience symptoms of heat illness like severe headache, nausea, or confusion, seek medical help immediately. 
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