Thursday, June 07, 2012

Where Summer Sucks Worse: Dubai

Last week, we highlighted the hot, hot heat that occurs at this time of the year in the Indian subcontinent thanks to the Monsoon pattern.  Well, take those temperatures...and ratchet up the humidity a few levels.  That's life along the Persian Gulf in the midst of summer.

Dubai is one of the many oil boom cities that have popped up along the Arabian Peninsula side of the Persian Gulf -- its boom and development into a major city having been fueled by oil.  Its position along the Persian Gulf to the north and west also provides it a perfect place to become a steam bath in the summer if conditions are just right as it is not only one of the hottest major cities on Earth...but can also become one of the most humid as well.

How nasty Dubai's summer heat gets depends on wind trajectory.  A wind off of the deserts to its east or south will provide a reduction in humidity levels, while a wind off of the toasty Persian Gulf brings additional humidity while only offering some "relief" in temperature.  The Persian Gulf's water temperature in the summer can reach 90 degrees, which means a wind off of the ocean isn't going to bring much relief but will bring a healthy dose of humidity to the equation.

So far in June, Dubai has had an average high and low of 99 and 81, pretty close to the historical averages of 102 and 81 respectively.  Toasty, for sure...and one may think that it's comparable to Phoenix when just looking at the temperature.

Let's add humidity to that equation though.

Last Friday's high in Dubai was 111, just like Phoenix, as Dubai was "enjoying" the benefits of a south-southwest breeze during the morning and midday hours.  The difference, despite the wind, was that Dubai's dew point remains relatively high thanks to its proximity to the Gulf (despite that offshore wind).  Dubai's dew point last Friday at its highest air temperature was 43, compared to Phoenix's 20ish dew points.  The heat index value was 106 in Dubai, 102 in Phoenix.  As the wind shifted in Dubai, temperatures "fell" to 95 but dew point values jumped quickly into the upper 70's, resulting in a late afternoon heat index in Dubai of 111.

And it can get worse.  Last July featured three days where the low did not drop below 95 and one where the low was just 96.  Phoenix at its worst only bottomed out at 90 a couple of times.  For that day with the 96 degree low, the heat index value in Dubai ranged from 95 in the middle of the night to 122 in late afternoon.

Such heat index values are "typical" summer in Dubai as they average a high temperature of 95 or higher from the end of April through the middle of October...besting Phoenix's range of mid May to the end of September.  Add a heavy dose of Persian Gulf warmth to the mix and you have a recipe for a place where some of the highest heat index values on earth can occur.

When we "sizzle" with our next cheap 90 degree high, remember it can be a lot worse!