Whenever we tell people how hot it is in Arizona, they respond, “Yeah, but it’s a dry heat.” In replying this way, they are usually thinking of the heat index and how humidity makes it feel hotter.
I’m from Ohio and I know that it can get pretty hot in the summer. On those hot days, the humidity can make you feel like some kind of swamp monster. States in the southeast have even more of those days through the year. Fortunately, at least in Ohio, the temperature might climb for a couple of weeks and then go back down before rising again.
Here in the Arizona Strip, the temperatures climbed above 90 in May and have stayed there day after day through July. June was the hottest, with a lot of days over 100. It has been cooler in July, with a couple of days below 90! Most of this cooler air is due to monsoon season, which I will explain tomorrow.
The average afternoon humidity in this part of the world is about 25%, definitely a dry heat. This is very low compared to Ohio, where the average afternoon humidity is 55%. St. Simons Island, where we spend the winters, has an even higher average humidity of 72%. So how hot does it feel in each of these places?
Most heat index charts start at 40% humidity, which is fine in Ohio or Georgia, but not so helpful in Arizona. I found this heat index chart which has low humidity levels on it. This is better for the relative temperature with dry heat. If it is 95 here in the Arizona Strip – a hot day – the “feels like” temperature is 93. In Ohio, the “feels like” temperature would be 109. In Georgia, that temperature feels like 123.
Granted, those are some dangerous temperatures and most people should limit their time outdoors. But Ohio and Georgia will also have cloudy days, whereas we don’t have many of those in Arizona. Now, I’ve always thought that the temperature is higher in direct sunlight. It feels hotter! But the air temperature is actually the same in the sun or the shade. The reason we feel hotter is the solar radiation which makes it feel 15 degrees hotter in the sun than in the shade.
No matter what it feels like, once the temperature gets above 90, it is just plain hot. The humidity may be high or low but people who are outside should take precautions. Drink plenty of water, wear a hat, and stay in the shade as much as possible. Know the symptoms of heat-related illnesses and stay safe.
Tom and I are enjoying our hot summer. But we are also taking precautions and going slow when it is really sunny or really hot. So, when it is hot, Hot, HOT – we are being careful!