Heat Advisory: Staying Safe During Extreme Temperatures

What Is a Heat Advisory?

A heat advisory is an official alert issued by the National Weather Service when heat-index values are expected to reach 100–104 °F for at least two consecutive hours. It signals an elevated risk of heat-related illness for the general public, especially for vulnerable groups. The advisory is often paired with an Excessive Heat Watch or Warning when conditions are more severe.

How Heat Advisories Are Issued

National Weather Service Process

Forecasters evaluate temperature, humidity, and duration using HeatRisk and official criteria. Alerts appear on weather.gov/slc/WWA and heat.gov dashboards in real time.

HeatRisk Color Scale

The HeatRisk tool offers color-coded guidance: green/yellow indicates low to moderate risk; orange/red signals high risk—consider activity modifications; and magenta denotes extremely high risk—limit outdoor exposure. Learn more.

Preparing Before a Heat Advisory

Check local forecasts via KSL Weather Alerts or AccuWeather Severe Weather Map. Stock water, electrolyte drinks, and cooling supplies, and identify air-conditioned locations such as libraries, malls, or cooling centers. Review safety steps on Ready.gov/heat.

Actions During an Active Advisory

Limit outdoor activities to early morning or evening hours. Wear lightweight, light-colored clothing and use sunscreen. Never leave children or pets in parked vehicles. Monitor neighbors and relatives who are elderly or have chronic illnesses.

After the Advisory Ends

Continue hydration and watch for lingering heat stress symptoms. Report any heat-related illness to local health departments and update emergency kits with lessons learned.

FAQ

How is a heat advisory different from an excessive heat warning?
A heat advisory covers lower—but still dangerous—heat-index levels; an excessive heat warning is issued for more extreme conditions that pose a higher threat of heat stroke.

Where can I see real-time alerts for my area?
Visit weather.gov/slc/WWA, heat.gov, or your local news site such as KSL.com/weather/alerts for the latest National Weather Service products.

What should I do if I don’t have air conditioning?
Spend several hours in a public cooling center, use fans with misting, and avoid the hottest part of the day indoors.

How does humidity affect heat advisories?
High humidity reduces the body’s ability to cool itself through sweat, so the “feels-like” temperature (heat index) rises, often triggering advisories even if air temperature is moderate.

Are certain groups more at risk?
Yes—older adults, young children, outdoor workers, athletes, and people with heart or respiratory conditions face higher danger during heat advisories.

Can I track national heat trends beyond local alerts?
Interactive tools like the New York Times Heat Wave Tracker and NOAA’s Climate Mapping for Resilience and Adaptation provide broader context on heat-wave patterns across the U.S.