Richard Angwin's World of Weather

It’s not the heat: beware the humidity

For at least four months of the year, the temperature here in Qatar reaches 40 degrees. Some days it is over 45 degrees. But, do you know what? You get used to it. You really do.

You learn to adapt. You try not to go out in it and if you do, you keep covered up. You park your car in any shade and if that’s not available you cover the inside of the car windscreen with a reflective shield. You don’t want your flesh melding to your steering wheel, do you.

What really gets everyone out here complaining is when the humidity starts to creep up. Heat and humidity do not make for healthy bedfellows.

Doha shimmers in the summer heat [Picture: Richard Angwin]

In Qatar the humidity tends to peak during the late summer. During the early summer, the sea temperature is relatively low and we often get a lot of shamal winds, which bring the dust but which are dry winds, due to their track across the Arabian Peninsula.

During late July and August, the shamals tend to disappear and we get the winds blowing from the east, bringing warm, moist air in off the Gulf.

Back home, a sea breeze is usually accompanied by a drop in temperature. Here, sea temperatures can be as high as 36 degrees.  (Trust me, I’ve recorded those sort of temperatures 20 metres down myself). So, there is no cooling effect. Instead it can be both very hot and very humid.

This can not only be very uncomfortable it can be life-threatening. I had personal experience of this a couple of weeks back when we drove across the desert to dive the Inland Sea. It was early morning, no wind, and the temperature was close to 40 degrees.

Nothing unusual there, but the humidity was very high and within a couple of minutes of leaving the air-conditioned car we were in, the sweat was pouring out of me.  And  I do mean ‘pouring’. I was perspiring far more than I would after a Dubai marathon.

After kitting up and dragging our gear to the water’s edge I was really feeling the strain. By the time we had finished our first dive I was struggling. When we had completed our surface interval I had just enough strength to get Renu kitted up and into the water but I felt I knackered.

I cancelled my dive and headed back to the shade where I drank and drank but it took more than an hour before my body temperature had cooled enough. (And jumping in the sea when the water is that hot does absolutely nothing to aid the cooling process – the Bristol Channel this is not!)

Heat index charts were developed in the late 1970s following work by Robert Steadman who was also responsible for wind chill. Like wind chill, the heat index takes into account factors such as body mass, clothing, sunlight and UV.

By combining these factors with air temperature and relative humidity it is possible to work out the risk of being outside in these conditions.

Whilst high heat indices are common across Southeast Asia, Central Africa, Central America and northern parts of South America, the highest heat index ever recorded was just up the road from us, in Dhahran, Saudi Arabia. On 8th July 2003 an air temperature of 42 degrees, combined with a dew point of 35 degrees resulted in a heat index of 68 degrees. That really is like a sauna!