Record Heat Index for continental US

[Humid Subtropical]

Originally Posted by wavehunter007

There is a map that shows what the record heat index is in most of the major cities - I'll try to find and scan it.

Would you mind posting this if you can find it?

[AdriannaSmiling]

Originally Posted by lpfan921

Wow! 148?? In Wisconsin? Wow. That's insane.

If a heat index of 148 has occurred in the U.S, and heat indexes over 130 F not being uncommon, that would mean an actual temperature of 155 F with a humidity of 1-2 percent would actually be more "survivable" than most people think.............So is my fictional climate of LOCO still "instantly lethel" as it has summer temperatures in the 150s range as averages but humidity levels around 1 percent?
//www.city-data.com/forum/weath...mate-loco.html

I would imagine that a 'dry 150 F' in LOCO (even though it has never been recorded in the real world) would be far more tolerable than the highest dewpoint ever recorded in the 'real' world- What was the highest heat index ever recorded in the world

[eagledrummer23]

To my understanding, the heat index is a subjective scale, calibrated to a particular dewpoint. For example, some heat indexes are calibrated to a 60 degree dew point, meaning when the dew point is 60, the heat index is equal to the dry bulb temperature. However, this means that low dewpoints, particularly in high temperatures, generate a heat index that is lower than the dry bulb temperature. Thus, the temperature feels lower than it actually is, because one assumes the observer is used to higher dewpoints. This is why heat indexes can vary from source to source. Dewpoint is a more reliable way to determine oppressive heat because it is an absolute humidity scale, as opposed to a relative humidity scale.

Dewpoint is a far more accurate way of determining the perceived temperature than dry bulb temp when dewpoints are above 60. This is how Houston, New Orleans, and Miami can generate astronomical heat indexes while never hitting triple digits, while Phoenix can post tempatures in the 120's and have a lower heat index.

[srfoskey]

Originally Posted by eagledrummer23

To my understanding, the heat index is a subjective scale, calibrated to a particular dewpoint. For example, some heat indexes are calibrated to a 60 degree dew point, meaning when the dew point is 60, the heat index is equal to the dry bulb temperature. However, this means that low dewpoints, particularly in high temperatures, generate a heat index that is lower than the dry bulb temperature. Thus, the temperature feels lower than it actually is, because one assumes the observer is used to higher dewpoints. This is why heat indexes can vary from source to source. Dewpoint is a more reliable way to determine oppressive heat because it is an absolute humidity scale, as opposed to a relative humidity scale.

Dewpoint is a far more accurate way of determining the perceived temperature than dry bulb temp when dewpoints are above 60. This is how Houston, New Orleans, and Miami can generate astronomical heat indexes while never hitting triple digits, while Phoenix can post tempatures in the 120's and have a lower heat index.

I disagree. If it's 105 with a dewpoint of 65, that'll feel hotter than if it's 85 with a dewpoint of 70. I think the heat index is a fair way to combine the two.

[unobtainium]

What about the Canadian"humidex"? https://en.wikipedia.org/wiki/Humidex

I've noticed it usually gives a higher estimate of how warm it feels, especially when high humidity kicks in at relatively mild temperatures (say in the 70s). Heat index is usually nada until temps climb higher, into the 80s. And yet in my experience, a relatively mild 74F with 90% humidity feels way warmer than 74F with 20% humidity. The humidex tends to reflect this, the heat index never seems to.