Climate & Environment

High Humidity Persists in UAE as October Nights Cool

By Huda Ata

The UAE is experiencing high humidity on Tuesday morning, a common pattern as temperatures drop overnight while moisture remains in the air, creating uncomfortable conditions and a higher chance of fog. According to the National Centre of Meteorology (NCM), moisture carried inland from the Arabian Gulf, combined with clear skies, light winds and falling overnight temperatures, leads to high humidity. As ground air cools, it approaches saturation, increasing the likelihood of fog. This pattern is expected as the country transitions from summer into autumn and toward winter. The NCM predicts that humidity will stay elevated throughout October, meaning cooler weather will not immediately end damp, sticky mornings. North‑westerly winds can bring Gulf moisture to coastal and inland areas during the evening and night; when these winds weaken, moist air can remain close to the surface. Clear skies allow the ground to lose heat overnight, cooling the air above it. As temperatures fall toward the dew point, relative humidity rises, even without additional moisture entering the air. Relative humidity measures how close the air is to saturation at its current temperature, so a cooler morning can have a higher humidity reading than a hotter afternoon. When saturation is reached, water vapour condenses into tiny droplets, forming fog. The NCM identifies relative humidity approaching 90–100 percent, sufficient moisture, calm conditions and falling surface temperatures as the main ingredients for fog. High humidity also makes warm weather feel more oppressive because sweat evaporates less readily, reducing the body’s ability to cool itself. Upper‑air conditions can prolong moisture build‑up; high pressure limits rising air, while overnight cooling can produce a surface temperature inversion, with cooler air below a warmer layer. This arrangement suppresses vertical mixing and keeps moisture near the ground, a situation associated with radiation fog, one of the most common types in the UAE. Wind speed also matters. Although north‑westerly winds can transport moisture inland, stronger winds can disrupt fog formation by mixing lower‑air layers. Their effect depends on strength and the moisture content of the air they bring. For those wondering when conditions will improve, there are two timescales to consider. Within a day, warming after sunrise can lower relative humidity and help disperse fog. An increase in wind can also break up the shallow layer of moist air. Neither process necessarily means the moisture has disappeared, and humid conditions can return overnight. Over the coming weeks, the NCM’s October outlook indicates that humidity will remain high. It lists the month’s average maximum relative humidity at about 78 percent, a climatic average rather than a ceiling on individual readings or a prediction for every location. The immediate forecast also points to humid conditions on Tuesday night and Wednesday morning over some coastal and inland areas, with a chance of fog or mist. Relief from the sticky conditions will depend largely on falling temperatures. Although humidity is expected to remain high through October, cooler weather should gradually make it feel less oppressive. High relative humidity can still occur on winter nights and mornings, contributing to fog without producing the same discomfort associated with summer heat. The NCM noted that fog occurs more frequently during December, January and February, which means the end of hot weather does not mean an end to humid conditions. October’s outlook also anticipates temperatures above the monthly average and rainfall slightly above average. The seasonal shift will be gradual, with warm days, humid nights and occasional fog continuing along the way.