Why UAE's heat and humidity persist: Insights into October's weather trends

Abu Dhabi residents experienced heavy humidity on Tuesday morning, a recurring seasonal pattern. Temperatures start to decrease overnight, but the air stays humid, leading to discomfort and potential fog. Moisture from the Arabian Gulf, clear skies, light winds, and falling overnight temperatures contribute to high humidity, according to the National Centre of Meteorology (NCM).

As the ground cools, air near the surface moves closer to saturation, increasing the likelihood of fog. The NCM predicts elevated humidity during October, so cooler temperatures won't immediately eliminate damp mornings. North-westerly winds can bring Gulf moisture to coastal and inland areas during evenings and nights; when winds subside, moist air remains near the surface.

Clear skies allow the ground to lose heat overnight, cooling the air above it, and when the temperature nears the dew point, relative humidity rises. This ascent in humidity can occur without additional moisture entering the air. When saturation is achieved, water vapor condenses into tiny suspended droplets, creating fog. High humidity exacerbates the feeling of warm weather because sweat evaporates less efficiently, diminishing the body's ability to cool itself.

High-pressure upper atmospheric conditions limit rising air, and overnight cooling can create a surface temperature inversion, with cooler air beneath a warmer layer, suppressing vertical mixing and keeping moisture near the ground - a characteristic of radiation fog, a common type in the UAE. Wind speed impacts fog formation; north-westerly winds can transport Gulf moisture inland, but stronger winds could disrupt fog by stirring the lower air layers.

The NCM's October outlook suggests that humidity will remain high, with an average maximum relative humidity of around 78 percent, a climatic average rather than a maximum for each location. Immediate relief from sticky conditions may come within a day as temperature increases after sunrise, lowering relative humidity and dispersing fog.

An increase in wind can also break up the moist air layer. While humidity is expected to stay high through October, cooler temperatures should make it feel less oppressive. High relative humidity can still cause fog on winter nights and mornings without the same level of discomfort experienced in summer.