Extreme heat above 90? That's the entirety of May-September pretty much in the South. This article is very skewed regionally. If you're a seasoned Southerner, my rule is don't exercise outside past 100 degrees temperature (which is at least 110 heat index) for more than 15 minutes in the sun if there's little or no shade. Even very fit people accustomed to it can get weak in that. And go before 8 am or after 6 pm or on an overcast day if you're doing 30 minutes or more. Or, of course, if there's ample shade like live oaks, I find I can walk an hour no matter how hot it is if I pour some water on the crown of my head under my hat before I go. Just be careful and mind what you're used to regionally and personally.
Extreme heat above 90? That's the entirety of May-September pretty much in the South. This article is very skewed regionally. If you're a seasoned Southerner, my rule is don't exercise outside past 100 degrees temperature (which is at least 110 heat index) for more than 15 minutes in the sun if there's little or no shade. Even very fit people accustomed to it can get weak in that. And go before 8 am or after 6 pm or on an overcast day if you're doing 30 minutes or more. Or, of course, if there's ample shade like live oaks, I find I can walk an hour no matter how hot it is if I pour some water on the crown of my head under my hat before I go. Just be careful and mind what you're used to regionally and personally.