Heat Warnings: What you need to know

Every summer, Arizona has a multitude of heat watches and warnings issued. And every year, we heard people grumble, “What’s the big deal? It’s Arizona…it’s hot. We know that already.”

The truth is, Excessive Heat Watches and Warnings are issued when the heat IS a big deal, meaning much higher than normal for the time of year. If temperatures are especially high, maybe 117 degrees or above, we’ll get a warning, issued by the National Weather Service (NWS) in Phoenix. But we can also see a heat warning issued if temperatures are not quite as hot, maybe 110 degrees, but for several days in a row. A long-duration heat event like this also puts more people in danger. And finally, we can see these warnings when temperatures are especially hot for a certain time of year. The criteria for the warnings are certainly different during the month of April versus the month of August.

So here’s what you need to know:

Excessive Heat Watch: We usually see these issued a few days before the especially hot weather arrives. Think of this as a heads-up that dangerous heat is expected in the next two to three days.

Excessive Heat Warning: This means dangerous heat is expected today or tomorrow.

I think it’s misunderstood that these watches or warnings mean the heat is dangerous for SOME people. The heat is dangerous for everyone. I was chatting with Dr. Frank LoVecchio the other day at the kick-off for our Hydrate Arizona campaign. He works in a local emergency room and sees cases of heat illnesses all the time. He told me it’s very hard for EVERYONE to acclimate to temperatures over 100 degrees. Spend too much time outside without enough water or shade, and you could be taking at trip to the ER yourself. He also advised drinking twice as much water as is normally advised during these summer heat episodes in Arizona.

Heat is the number one cause of weather-related deaths in the United States. In Maricopa County, an average of 70 people a year die because of heat.

NWS is testing out a new scale, called “Heat Risk,” to help Arizona residents understand the danger of heat. The 0-4 scale is color-coded, similar to the UV Index and the Air Quality Index. The categories give a bit more detail on who could be affected by the heat that day, with the goal of helping people take action and make decisions that will keep them safe.

On average, Phoenix gets 110 days of 100-degree and higher heat each year. We get an average of 19 days at or above 110 degrees. So this is just the beginning. But hopefully, the monsoon is just around the corner and will bring some relief in the form of rain!