Dangerous heat was still affecting parts of the Southwest and Southeast on July 8, 2026, according to the National Weather Service homepage. If your weather app shows a high temperature, that number is only part of the planning picture. The NWS HeatRisk map is meant to answer a more practical question: how much stress could the heat place on people who are outside, without cooling, medically vulnerable, or not yet acclimated?
HeatRisk is useful because it combines forecast heat with how unusual that heat is for the location and time of year. It does not replace official heat watches, warnings, or advisories, but it can help you decide whether a walk, commute, job shift, sports practice, travel day, or check-in call needs to change before the hottest part of the day arrives.
The short answer
Start with the color, then check the official alert. Green means little to no heat risk for most people. Yellow means minor risk, especially for people who are unusually sensitive to heat. Orange means a moderate risk level where some people may need to change plans. Red means major risk and calls for stronger precautions. Magenta means extreme risk and should be treated as a serious warning sign for anyone exposed to heat for long periods.
How the colors work
The Weather Prediction Center describes HeatRisk on a 0 to 4 scale. The scale is designed to show potential heat-related impacts, not just the afternoon high. That matters because the same temperature can carry different risk in Phoenix, Atlanta, Minneapolis, or Seattle, depending on humidity, overnight cooling, local norms, and how prepared people are for heat.
- Green, level 0: Little or no risk from expected heat for most people.
- Yellow, level 1: Minor risk, mainly for people who are very sensitive to heat or lack cooling.
- Orange, level 2: Moderate risk, when heat can affect people who are exposed for a long time or have added health risks.
- Red, level 3: Major risk, with more people likely to need heat precautions.
- Magenta, level 4: Extreme risk, often tied to rare or long-duration heat with little relief.
What to do with each level
At yellow, make a small adjustment: carry water, choose shade, and avoid assuming a short errand is harmless for an older relative, a young child, a pet, or someone taking medicine that affects heat tolerance. At orange, move strenuous activity earlier or later, build in cooling breaks, and check whether a workplace, school, camp, or event has changed its schedule.
At red or magenta, treat heat as a day-shaping hazard. Reschedule outdoor exercise, limit unnecessary trips, find an air-conditioned space, and check on people who may not ask for help. The CDC advises staying cool, staying hydrated, and watching for signs of heat illness. It also warns that fans alone may not prevent heat-related illness when indoor temperatures are very high.
Check these details before you act
HeatRisk is one layer. Before changing plans, check your local NWS forecast office for watches, warnings, and advisories; your city or county emergency management page for cooling centers; and the CDC Heat and Health Tracker if you need a health-focused view. Air quality can also change the decision, especially for people with asthma, heart disease, or outdoor work.
Pay attention to overnight lows. A hot day followed by a warm night can raise risk because homes, sidewalks, and vehicles do not cool down enough. That is one reason a moderate-looking forecast can still become dangerous for people without reliable air conditioning.
What to watch
HeatRisk maps can change as forecasts update, so check again in the morning if you made plans the night before. If the color moves from orange to red, treat that as a cue to shorten exposure, add cooling breaks, or move plans indoors. If an official warning is issued, follow the warning first. The simple rule is this: use HeatRisk to plan early, then use local alerts to make the final call.
