It's that time of year when some spots around the globe get so hot their virtually unliveable.

Top spot so far (this year I think) is Basra, today reaching an almost unthinkable 53C. Weatheronline link below - hasn't yet updated for the latest reading.

http://www.weatheronline.co.uk/weather/maps/current?LANG=en&UP=0&R=310&TYP=tmax&ART=tabelle&LANG=en&DATE=1469104200&KEY=asie&LAND=asie&CONT=__&SORT=3&SI=mph&CEL=C&UD=0

All the action seems to be in the gulf at the moment although Death Valley is not far behind with maxes in the high 40s this week.

Lots of heat across America at the moment, I think most of the country is in the 90s and 100s. Quite a widespread heat dome even by there standards. Death Valley had its moment last month with the 50c+ temps. Not that hot at the moment though.

Ties the record with Death Valley. I can't even comprehend temps like that though I would like to experience something like that for one day.

I've experienced 56C - in the conservatory 😏

Humidity was certainly much higher then what you find in the desert like Kuwait or Death Valley, and i only lasted 5 minutes.

Profusely sweating within seconds and I also found breathing felt somewhat laboured. The heat literally sucked the energy from you.  

The worst thing about Kuwait and Coastal Southern Iraq is that they are sometimes also very humid, though not this week it seems. The gulf is like a big warm bath.

Here is a synoptic chart showing that portion of the northern Gulf area yesterday at 1200 GMT. Air temperature is upper left on the station plot and 53C can be seen at 40689 which is Basrah. Station 40831 a short way to the southeast is Abadan which has a long and consistent record (as do many of the Iranian stations). The maximum temperature recorded at Abadan was 51.0C and at Ahwaz 50.4C, so for the Iraqi stations to exceed the Iranian ones by several degrees seems a little unusual and worthy of further study.

Hafr al-Batin in Saudi just to the west of Kuwait recorded a max of 50.0C. This station lies at 350m above sea level so assuming DALR to the surface then this would tend to support the max of 53C near sea level, inland from the sea breeze zone. The 850mb temperature from the 12z sounding at Hafr al-Batin was 35.6C. Assuming 17C to sea level yields a potential max of 52.6C so ingredients were certainly there for these high maxes.

Some of the stations right on the coast show air temperature 35-36 with a dewpoint of 30-31C. This is getting on for the highest humidity levels in the world. I spent 10 years in Abu Dhabi and the highest temp/dewpoint combination I saw there was 37C/32C yielding a wetbulb of just under 34C. The feeling of the air at these levels is impossible to describe, but never forgotten once experienced!

I've been in central Florida in high summer with evening air temperatures in the high 20's.. Low 30's with 100% humidity 😊

I absolutely loved it... Simply putting it nothing evaporated.

So the highest possible dewpoints are a good few degrees below body temperature. I'm sure us humans (and indeed other animals) have evolved with this in mind. If you had a dewpoint above 37C water would condense in your lungs and you'd drown!

This is exactly the point. The important factor is the wet bulb temperature as this determines the level at which heat can be lost from the human body due to evaporation of sweat.

The skin temperature of a normal human is several degrees cooler than the core which is around 37C. Various estimates are out there but 33-34C seems to be a typical value. If the wet bulb is above this skin temperature then the body cannot lose heat by evaporation and so will continue to heat up into heatstroke levels if exposed to the sun or engaging in physical activity.

34C is the highest wet bulb temperature recorded anywhere in the world, so it does seem that humans have evolved to withstand these extreme levels of heat and humidity. It's no coincidence either that the sea surface temperature in the Gulf at this time of year is 33 to 34C in open water. It all ties in together.

Mention of evolution reminds me that there is a theory that humankind is the only species to be able to lose substantial amounts of heat through sweating (as opposed e.g. to panting) . Hence the ability to keep cool during a chase enabled our ancestors to outrun and out-predate the quarry which was getting heatstroke.