The most dangerous / frequent occurrences seem to be measured in the middle east near shallow gulf coasts. Appleton Wisconsin holds the continental US record, apparently?
> The highest dew points, and therefore the highest heat indices are usually found near warm bodies of water.
> In the world, the warmest water is found in the Persian Gulf where the water temperature typically reaches up to 90°F (32°C) in summer. Therefore dew points will be that high as well.
> The highest dew point ever recorded, 95°F (35°C), was recorded at Dhahran, Saudi Arabia, on July 8, 2003. With an air temperature of 108°F (42°C) the heat index was 178°F (81°C).
> In the United States, the highest dew point ever recorded, 90°F (32°C), was recorded at the New Orleans Naval Air Station, on July 30, 1987, Melbourne, Florida on July 12, 1987. Heat indices were in the 130's°F (50's°C).
> Appleton, Wisconsin also had a 90°F (32°C) dew point on July 13, 1995 with a heat index of 149°F (65°C)."
https://www.wunderground.com/blog/weatherhistorian/record-de...
The most dangerous / frequent occurrences seem to be measured in the middle east near shallow gulf coasts. Appleton Wisconsin holds the continental US record, apparently?
This is from 2011.
This looks more updated: https://www.weather.gov/jetstream/hi
and says:
> The highest dew points, and therefore the highest heat indices are usually found near warm bodies of water.
> In the world, the warmest water is found in the Persian Gulf where the water temperature typically reaches up to 90°F (32°C) in summer. Therefore dew points will be that high as well.
> The highest dew point ever recorded, 95°F (35°C), was recorded at Dhahran, Saudi Arabia, on July 8, 2003. With an air temperature of 108°F (42°C) the heat index was 178°F (81°C).
> In the United States, the highest dew point ever recorded, 90°F (32°C), was recorded at the New Orleans Naval Air Station, on July 30, 1987, Melbourne, Florida on July 12, 1987. Heat indices were in the 130's°F (50's°C).
> Appleton, Wisconsin also had a 90°F (32°C) dew point on July 13, 1995 with a heat index of 149°F (65°C)."
So, it happened once, in Saudi Arabia?